Here's what we know: an overwhelming majority of scientists tell us that the Earth's climate is heating largely due to rising greenhouse gas emissions, which, in turn, is driving more extreme weather and climate events. The underlying changes -- warmer oceans, more intense precipitation events, and rising sea levels -- are significant contributors to storms like Sandy. Around the world, we're seeing heavier rainfall and record-breaking high temperatures, and many areas are experiencing more severe droughts and more wildfires. These patterns are precisely what climate scientists have said we should expect in a warming world. Further, these extreme weather and climate events are taking a serious toll as they disrupt people's lives and our economy.

The human and economic costs of Hurricane Sandy and other extreme weather events are abundantly clear. In 2011, according to the National Oceanic and Atmospheric Administration, there were 14 extreme weather and climate events of more than $1 billion in the United States, totaling approximately $55 billion. Looking at the bigger picture, a recent report found that the failure to act on climate change is likely to cost the world economy 1.7 percent of GDP, approximately $1.2 trillion per year in the near term, with the figure expected to double by 2030.

What climate change does is make many "natural" events more frequent and worse. By continuing to pump millions of tons of carbon pollution into our atmosphere every single day, we are throwing Earth's complex climate system out of whack, and this is the price we pay. Science tells us that the destructiveness of this storm was fueled by climate change -- driving higher sea levels that pushed up storm surge, and higher ocean temperatures that contributed to the monstrous size of the storm and loaded extra rain into the clouds. Science has identified another powerful potential factor: The record-breaking melting of Arctic sea ice's impact on the jet stream may have created the block of high pressure above Greenland that drove Sandy west into the continental United States, rather than allowing it to spin off east into the North Atlantic, as most late-season hurricanes do.

"Climate change is changing the weather," Trenberth said. "The past few years have been marked by unusually severe extreme weather characteristic of climate change. The oceans are warmer and the atmosphere above the oceans is warmer and wetter. This new normal changes the environment for all storms and makes them more intense and with much more precipitation." Rising temperatures are also likely to intensify other storm phenomena. Thunderstorms may become less frequent but more intense, for example. And all that extra moisture also increases the threat of inland flooding, as happened after Hurricane Irene passed over the East Coast last year, contributing to the lion's share of roughly $16 billion in total damages. Add to this that the fact that ocean surges associated with such storms now ride on sea levels that have risen over the last century, and the potential for catastrophic losses is plain.

"We've warmed the planet," he said. "Everybody knows we've warmed the planet. So all super-storms are related to climate change now. You can't have a super-storm that's not related to climate change. Does everyone agree that the oceans have warmed? That land temperatures have increased? That there's more moisture in the air?" Tidwell posited. "The answer is yes. So it's impossible to have a super-storm that doesn't have the fingerprint of climate change on it."

Extreme weather events helped raise food prices and fuel price volatility in 2007–08 and 2010–11,4 and climate scenarios predict more variable weather events in the future.5 More intense and frequent natural disasters (such as droughts and floods) resulting from climate change could trigger significant yield losses and subsequent price increases and higher volatility. Indeed, IFPRI simulations show that climate change is likely to push prices up, regardless of whether population (and thus demand for food) grows faster or slower.

Food prices will more than double and the number of malnourished children spiral if climate change is not checked and developing countries are not helped to adapt their farming, food and water experts warned on Tuesday at the UN climate talks in Doha.

Informed that scientists at both the National Oceanic and Atmospheric Administration and the Environmental Protection Agency linked the record heat and drought of summer of 2012 with man-made climate change, Schulz says this is news to him. Nevertheless, he holds firm to his conviction that climate change is a ruse to justify greater government regulation: “I just don’t think we’ve got enough data to say climate change is real.” Not everyone is sticking his head in the sand. Barilla, the largest pasta company in Italy, claims to be taking a number of measures. To limit its climate-related risks, says spokesperson Marina Morsellino, Barilla is globally diversifying its supply chain so that bad weather in one region does not leave the company without adequate supplies of durum. It is also “developing new varieties more resistant to ... extremely dry or wet conditions,” she adds, while encouraging farmers to employ such traditional practices as rotating durum with numerous other crops, a strategy Morsellino says can reduce greenhouse-gas emissions by 55 percent.

There is an overwhelming level of scientific consensus on human-caused climate change. Over 95% of actively publishing climate scientists agree that the earth is warming and that human activity is the cause. In spite of this agreement, only about 50% the general public think that scientists have reached a consensus on human-caused climate change. Two sources of the discrepancy are the unbalanced portrayal of the situation in the media, and the Manufactured Doubt Industry.

We must demand that they acknowledge the reality of climate change, how we are causing it and how it is changing our world, and agree on a path to solve this problem. That path means stopping our contributions to climate change -- a cessation that scientists say is possible only if we can agree, as a society, to change the way we extract and use energy.

The fossil fuel companies have played the biggest role in making sure we don't slow global warming down. They've funded climate denial propagandists and helped pack Congress with anti-environmental extremists, making sure that commonsense steps to move toward renewable energy never happen.

The depleting ice cover would have serious ramifications for the planet. Arctic ice acts as a reflector of sunlight, helping regulate Earth's temperature, cooling the climate. "When there's no longer that sea ice below the air mass and it's just open ocean, that's when more moisture off the ocean's surface gets into the atmosphere and the water vapor in the atmosphere makes for more violent storms," says Yackel. "We can also expect to see an increase in storm frequency and storm intensity for most of the world's populated places as the Arctic and Earth continues to warm."

"Climate models have predicted a retreat of the Arctic sea ice; but the actual retreat has proven to be much more rapid than the predictions," said Claire Parkinson, a climate scientist at NASA Goddard Space Flight Center, Greenbelt, Md. "There continues to be considerable inter-annual variability in the sea ice cover, but the long-term retreat is quite apparent." The thickness of the ice cover is also in decline.

Charles G. Koch and David H. Koch have a vested interest in delaying climate action: they've made billions from their ownership and control of Koch Industries, an oil corporation that is the second largest privately-held company in America (which also happens to have an especially poor environmental record).

Rising temperatures also threaten Western agriculture, with a particularly large effect on premium wine-grape-growing regions. Grapes are an interesting case, requiring what Diffenbaugh called a "very narrow climate envelope" – they can't be too cold or too hot. Unfortunately, modeling shows that climate change threatens to wipe out far more wine country than it will create.

We know that the decisions we are making today are on track to create irreversible and inexorable changes in the global climate that our children and their children will inherit. We know that those changes threaten to slow or reverse our hard-fought gains in peace and health, leaving our descendants a world in violent, unceasing transition, with rising seas, greater droughts, more intense storms, shifting zones of fertility and disease, and waves of climate refugees. We discovered this not through shock or confrontation but through the slow accumulation and careful interpretation of evidence. It is still, to most people, almost entirely an intellectual phenomenon, something they know but do not feel.

Perhaps the most important message from Sandy is that it underscores the enormous price of underestimating the threat of climate change. Damage increases exponentially even if preparations are only slightly wrong. In trying to protect Grand Forks, N.D., from a spring flood in 1997, the city used sandbags to defend against a high-water mark of 52 feet, comfortably above the 49-foot crest predicted by the National Weather Service but, unfortunately, below the 54-foot crest that occurred on April 21. It was only 10% higher than what was expected, but the damage was many hundred times greater than if the protections had not been breached; 50,000 homes suffered damage.

“We’re in uncharted territory,” says James Overland of the University of Washington. The weakening jet stream means “wild temperature swings and greater numbers of extreme events”. The last time the Arctic is believed to have been ice-free is during the Eemian period, about 125,000 years ago, when global sea levels were between four and six metres higher than today. However, current atmospheric CO2 levels are already far higher than during the Eemian; indeed, you would have to go back several million years to find any era in the Earth’s history to match today’s levels of this powerful heat-trapping “greenhouse gas”.Lags in the system mean that we have so far experienced only the very mildest of the effects of the ever-growing heat imbalance in our climate system.

But there might be a less dramatic reason than polar ice melting for the higher ocean level -- the higher temperature of the water. Water is most dense at 4 degrees Celsius. Above and below this temperature, the density of water decreases (the same weight of water occupies a bigger space). So as the overall temperature of the water increases it naturally expands a little bit making the oceans rise.In 1995 the Intergovernmental Panel on Climate Change issued a report which contained various projections of the sea level change by the year 2100. They estimate that the sea will rise 50 centimeters (20 inches) with the lowest estimates at 15 centimeters (6 inches) and the highest at 95 centimeters (37 inches). The rise will come from thermal expansion of the ocean and from melting glaciers and ice sheets. Twenty inches is no small amount -- it could have a big effect on coastal cities, especially during storms.

One of the curious features of the latest set of data is that Antarctic sea ice has seen a record expansion. According to NSIDC the reasons for this are ‘complex and surprising’ but are inextricably linked to global climate change.

NSIDC scientist Ted Scambos said, "Antarctica's changes—in winter, in the sea ice—are due more to wind than to warmth, because the warming does not take much of the sea ice area above the freezing point during winter. Instead, the winds that blow around the continent, the "westerlies," have gotten stronger in response to a stubbornly cold continent, and the warming ocean and land to the north." Researchers believe that climate change has created a "wind wall" that keeps the cold around the South Pole while the rest of the globe is warming.

When we burn fossil fuels -- oil, coal and gas -- to generate electricity and power our vehicles, we produce the heat-trapping gases that cause global warming. The more we burn, the faster churns the engine of global climate change. Thus the most important thing we can do is save energy.

Arctic sea ice is an important component of the global climate system. The polar ice caps help to regulate global temperature by reflecting sunlight back into space. White snow and ice at the poles reflects sunlight, but dark ocean absorbs it. Replacing bright sea ice with dark ocean is a recipe for more and faster global warming. The Autumn air temperature over the Arctic has increased by 4 - 6°F in the past decade, and we could already be seeing the impacts of this warming in the mid-latitudes, by an increase in extreme weather events. Another non-trivial impact of the absence of sea ice is increased melting in Greenland. We already saw an unprecedented melting event in Greenland this year, and as warming continues, the likelihood of these events increase.

Dr. Zhang explained that climate change has caused sea ice to retreat markedly in recent decades and has also warmed Arctic Ocean temperatures. Such changes may be providing more energy and moisture to support cyclone development and persistence. The strong storms of this week and a month ago would have had far less impact on the ice just a decade ago, when the sea ice was much thicker and more extensive.

The Arctic sea ice, essentially, it is a big reflector of solar energy during the summer, and that keeps the Arctic cooler than it normally would be. It acts like an air conditioner in a sense for the Earth's climate system. And that helps not only keep the Arctic cooler, but also the globe as well. And it's basically a sink for heat that comes in at the equator, gets transported to the north. And then you lose the heat in the Arctic. And those -- that transfer of heat from the equator to the poles, that essentially helps set up things like the jet stream, our prevailing winds, our weather tracks. And so as we start to lose the ice cover and we warm up the Arctic, essentially, that's changing the balance between the equator and the poles. And that will shift things like storm tracks and the jet stream, and that will change weather patterns.

Ed Davey, the UK climate and energy secretary, said: "These findings highlight the urgency for the international community to act. We understand that Arctic sea-ice decline has accelerated over recent years as global warming continues to increase Arctic temperatures at a faster rate than the global average.

But the long-term consequences of the ice loss are far more substantial and far more difficult to predict, says Masters. The reason? The jet stream, the fast-flowing river of air that helps to regulate temperatures and weather patterns across much of North America and parts of Europe.Many climate scientists believe the jet stream could change in major ways thanks to warming temperatures and shrinking ice in the Arctic. By moving cold and warm air around the earth, the jet stream helps even out its overall temperature. If the Arctic gets warmer, there’s no need for the jet stream to move as quickly as it does now.“If you’ve got more heat in the Arctic, the jet stream decreases in strength,” he added. “When the jet stream slows down, now that means that when you have an extreme period of weather, it tends to hang around longer.”

CALL me a converted skeptic. Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming. Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause.

The second thing to fear about loss of Arctic sea ice is the potential to accelerate climate change on a global basis.

The radical decline in sea ice around the Arctic is at least 70% due to human-induced climate change, according to a new study, and may even be up to 95% down to humans – rather higher than scientists had previously thought.

A UN report issued at climate change negotiations in Doha, Qatar, found that human greenhouse gas emissions were triggering the Arctic thaw.

Higher sea levels. More intense storms. Drought.These are the most common impacts associated with climate change.

Less burning of fossil fuels (gasoline) reduces the carbon dioxide emissions that cause global climate change. Human pedaling is an infinitely renewable resource; gasoline is not.

Scientists know that climate change has increased Earth's temperature, and that it has fueled more heat waves, more intense precipitation, more intense droughts and more wildfires. They're confident those extremes will soon become the new norm.

We just assume when we turn on the tap, the water will be there, and that the water system buried in the ground is doing fine. Both assumptions are out of date. Population growth, economic development (which changes dramatically how much water people want and use), and climate change are all putting pressure on water supplies — not just in places like Las Vegas or California, but in Atlanta, in Florida, in Spain, across China.

One of the world's leading naturalists has accused US politicians of ducking the issue of climate change because of the economic cost of tackling it and warned that it would take a terrible example of extreme weather to wake people up to the dangers of global warming.

Yet he also warned that it was becoming clear the impacts of climate change were worst than had been expected. Talking about the record Arctic sea ice melt this summer, he said: "The situation is worse than we thought [in the Arctic]. The processes of melting are more volatile than we thought. More complicated. The ice cap is really melting faster than we thought."

It is difficult to overstate the magnitude of what is currently unfolding in the Arctic regionTHE TRUTH, as Winston Churchill put it, is incontrovertible. “Malice may attack it, ignorance may deride it, but in the end, there it is.” Scrape away the layers of denial, obfuscation and spin that cloud climate change and one unvarnished truth emerges: the Arctic ice cap is dying – and, with it, humanity’s best hopes for a prosperous, predictable future.

The sheet of ice that covers the North Pole melted to its smallest size on record in late August, shattering the previous record set just five years ago and providing a strong sign of the long-term warming of the earth's climate."This is happening before our very eyes," said Jennifer Francis, a research professor with the Institute of Marine and Coastal Sciences at Rutgers University. "It’s not something that’s happening decades from now or generations from now. It’s real and it’s now."

A prominent physicist and skeptic of global warming spent two years trying to find out if mainstream climate scientists were wrong. In the end, he determined they were right: Temperatures really are rising rapidly.

Climate change is driving more extreme weather – by heating up the atmosphere, pumping more energy into storms, and heating the air to the point that it can more easily suck away moisture or concentrate it in one point.  As the planet continues to warm, all of those factors will increase, leading to more heat waves, more droughts, and more floods. And the changes to the Arctic, it seems, will exacerbate this, by slowing down the jet stream, and making it more likely that the extreme weather conditions that develop get locked in place, hammering the same regions for protracted lengths of time.

A new NASA-funded study by the National Center for Atmospheric Research, Boulder, Colo., finds climate model projections that show a greater rise in global temperature are likely to prove more accurate than those showing a lesser rise.

By 2035, global energy demand is forecasted to increase by over a third. The EIA estimates this energy consumption increase will generate enough new greenhouse gases to raise climate temperatures by 3.6 percent.

Intense heat. Disappearing snowpack. We know that the environment of the American West is going to be hard-hit by climate change. Rising temperatures aren't good if you're, say, a delicate salmon egg or a mountain yellow-legged frog. But these changes also carry consequences for the region's economy.

This year’s Intergovermental Panel on Climate Change (IPCC) assessment report states that “increases in the frequency of droughts and floods are projected to affect local production negatively, especially in subsistence sectors at low latitudes.” The decline in production in the face of growing demand can drive up prices in markets that may lack the technology to fight environmental hazards to overall production.

Staple food prices may double within the next two decades due to climate change and an increase in extreme weather including droughts and hurricanes, the anti-poverty group Oxfam said Wednesday.

A recent study commissioned by Oxfam into global warming and food prices, said: "Against a backdrop of rising populations and changing diets which will see global food production struggle to keep pace with increasing demand, the food security outlook in a future of unchecked climate change is bleak."

Three grains—wheat, corn, and rice—account for most of the food humans consume. All three are already suffering from climate change, but wheat stands to fare the worst in the years ahead, for it is the grain most vulnerable to high temperatures. That spells trouble not only for pasta but also for bread, the most basic food of all.

We also need, desperately, to limit global warming, because even the most skillful adaptation measures cannot cope with 7˚F of global temperature rise. That means the federal government must stop ignoring the mounting climate crisis and take swift aggressive action to slash greenhouse gas emissions.

For centuries, Morris says, climate change has accompanied massive social change, upheavals ranging from the fall of the Roman Empire to the spread of the Black Death throughout Europe in the 1300s. Morris suggests that environmental and cultural events indicate the world might be heading for yet another transformation. Already, global warming is hurting parts of central and eastern Asia; Pakistan’s recent devastating floods are a case in point, Morris says. And he cited a respected British report cautioning that more negative environmental events could unleash as many as 200 million “climate migrants,” people who are desperately “driven by water and food shortages, undermining states as they go, and setting off wars.”

“One of the big things historians and archeologists have been able to show is that climate change alone never causes anything in a straight-forward sort of way. It’s human response to climate change that drives the change, and that is something we can do something about,” Morris said. “We can shape these views, so if people understand what’s happening around them, they can respond constructively.”

With global warming on the rise and species and their habitats on the decline, climate change is perhaps one of the greatest threats the planet faces today. Climate change is perceived as the presence of more diseases, more rainfall, change in climatic conditions and loss of agricultural output. But amid all the brouhaha about its deleterious effects on planet earth, a fact that has failed to find resonance is that global warming isn't gender-blind — women are especially vulnerable to its effects

Ultimately, history will judge us on whether we have reduced greenhouse gases enough to avoid the worst climate change. The fact is that we can do this right now in ways that both boost the economic sustainability of everyone and at the same time safeguard those most vulnerable to the adverse effects of climate change.

Many scientists believe the atmospheric concentration of those gases must be kept below 350 parts per million to avoid dramatic and runaway changes in our climate. That benchmark has already been passed.

"We can't blame the existence of a single hurricane on global warming, just like a die weighted to roll sixes can't be blamed for any single roll of a six," said Michael Mann, a physicist and the director of the Earth System Science Center at Pennsylvania State University. Sixes, after all, will sometimes happen anyway, even when the dice aren't loaded, Mann explained. "But we can see that climate change is playing a role in setting the context for these storms," Mann continued, "in particular the record levels of North Atlantic ocean warmth that is available to feed these storms with energy and moisture."

The most palpable impact of climate change for those of us who live far from the poles is the increase in extreme weather. Around the world, record highs are occurring at more than twice the rate of record lows. The US drought of 2012 was the worst since the Dust Bowl of the 1930s. A drought nearly as bad struck Texas and the American south in 2011, and even more destructive heat waves hit China and Russia in 2010, and Europe as a whole in 2003.

If we deal with climate change, it’s good for the country. We create new industries. We create new job possibilities, we create a healthier air supply for us to breathe and we can stabilize some of the geopolitical risks that are inherent in this. There’s lots of positives that come from addressing the excess burning of fossil fuels and treating that beautiful cerulean air supply out there as a garbage dump where for free, we can throw our refuse. We’ve been doing that for four million years and we can’t afford to do that anymore.

The shift toward low carbon requires global participation because every country is already affected by climate change and because of the need to deliberately guide an accelerated global changeover. Furthermore, the scale and pace of economic development driven by technology and the free movement of capital makes global participation essential. The low-emission economies of today will become high-emission economies of tomorrow faster than was ever possible unless they are adequately supported and encouraged to engineer clean energy futures.

Past energy transitions have taken a long time to unfold. Firewood was mankind's first energy source and was not displaced by coal until the 18th century. With an increasing pace of technological advance, it took one century for oil to replace coal as the primary global energy source. Climate change is not the only motivation to move toward more renewables and enhanced energy efficiency, but it has injected unequivocal urgency into an otherwise normal evolution.

Natural gas will also peak shortly and since it helps make 97 per cent of the world’s nitrogenous fertilizer, an N scarcity is also on the cards. Using coal to make fertiliser does not seem smart, as its contribution to climate change is to create more drought and hence lower crop yields.

To stop the world’s temperature from rising more than 2 degrees Celsius (3.6 degrees Fahrenheit) above the pre-industrial era — considered by most climate scientists as the prudent limit — emissions must fall much faster. In fact, keeping to the target probably requires that a good share of the world’s fossil fuel remains untapped.

Estimates by the Potsdam Institute for Climate Impact Research in Germany — reported by the Carbon Tracker Initiative in Britain — suggest that to keep the odds of exceeding the 2-degree ceiling below 20 percent, no more than 565 billion tons of CO2 can be put into the air over the next 40 years. That would require cutting the world’s total emissions by more than half, to about 14 tons a year. Look at it this way: the world’s carbon intensity — the amount of carbon emitted into the atmosphere for each dollar of economic production — fell about 0.8 percent a year over the last decade or so. According to a study by PricewaterhouseCoopers, avoiding a 2-degree rise requires a decline in emissions of 5.1 percent a year — every year until 2050. As the PricewaterhouseCoopers study suggests, it might be “too late for 2 degrees.”

It is difficult to overstate the magnitude of what is now unfolding in the Arctic region. The Arctic ice cap used to cover 2 per cent of the Earth’s surface, and the ice albedo effect meant vast amounts of solar energy were bounced back into space from the bright white ice mass.Losing this ice, and replacing it with dark open ocean, creates a dramatic tipping point in planetary energy balance.“The extra radiation that’s absorbed is, from our calculations, the equivalent of about 20 years of additional CO2 being added by man,” Prof Wadhams said.With global carbon dioxide (CO2) emissions already spiralling far beyond the levels that scientists have warned present grave risks to humanity, the injection of a massive new source of additional energy into Earth systems could hardly have come at a worse time.

Average temperatures in the Arctic region are rising twice as fast as they are elsewhere in the world. Arctic ice is getting thinner, melting and rupturing. For example, the largest single block of ice in the Arctic, the Ward Hunt Ice Shelf, had been around for 3,000 years before it started cracking in 2000. Within two years it had split all the way through and is now breaking into pieces.

The shrinking of the ice cap was interpreted by environment groups as a signal of long-term global warming caused by man-made greenhouse gas emissions. A study published in July in the journal Environmental Research Letters, that compared model projections with observations, estimated that the radical decline in Arctic sea ice has been between 70-95% due to human activities.

The study of the world's surface temperatures by Richard Muller was partially bankrolled by a foundation connected to global warming deniers. He pursued long-held skeptic theories in analyzing the data. He was spurred to action because of "Climategate," a British scandal involving hacked emails of scientists. Yet he found that the land is 1.6 degrees warmer than in the 1950s. Those numbers from Muller, who works at the University of California, Berkeley and Lawrence Berkeley National Lab, match those by the National Oceanic and Atmospheric Administration and NASA.

You might not think that what happens in the Artic has much bearing on what happens in Texas or Moscow or southern provinces of China, but a study published in 2012 in Geophysical Research Letters has drawn a convincing connection. Blowing around the periphery of the Arctic is the polar jet stream – a region of high speed wind that blows west to east, and helps drive wind circulation around much of the northern hemisphere.  The jet stream is powered by the temperature difference in fall and winter between the Arctic and the more temperate areas just to its south. But as the Arctic ice has receded, the Arctic Ocean waters have absorbed more heat in late summer and early fall.  In late fall and early winter, they’ve given that heat up, back into the atmosphere. That, in turn, has led to warmer Arctic autumns and winters, which has reduced the temperature difference that fuels the jet stream. The result is that the jet stream is now weaker than it once was – about 14% weaker than it was in 1980. Why does this matter? Because a slower jet stream makes it easier for ‘blocking’ weather patterns to develop.  Blocking weather patterns are the ones that hover over a region rather than moving on – like the drought that basted Texas in 2011 and decimated its forests and hay and wheat crops to the tune of more than $7 billion in damage, and like the heat wave that enveloped Moscow and much of the rest of Russia for most of the summer of 2010, killing an estimated 55,000 people in July and August of that year.

the complete meltdown of the Arctic could roughly double the rate of warming of the planet as a whole.

Pedal power is the transfer of energy from a human source through the use of a foot pedal and crank system. This technology is most commonly used for transportation and has been used to propel bicycles for over a hundred years.

But beyond the personal advantages, the real benefit of committing to the morning cycle commute is rooted in energy use. Each day we consume odious amounts of energy transporting people a few miles to work. While this may seem like the most expedient option, it’s not the most sustainable in the long term. There must come a time when we take steps to limit our environmental footprint – and biking is one of the best ways to do so. It’s green, emissions free, and the only byproduct is a stronger set of thighs.

This research shows how extreme weather events in a single year could bring about price spikes of comparable magnitude to two decades of long-run price rises. It signals the urgent need for a full stress-testing of the global food system in a warming world.