Can We Really Say Climate Change Is to Blame for Typhoon Haiyan?

The Philippines has been hit by 24 typhoons in the past year but the power of Haiyan was off the scale, killing thousands and leaving millions homeless. Is there even worse devastation to come?

Photo Credit: AFP

Just as the world was beginning to take in the almost unimaginable devastation wrought by typhoon Haiyan, a young Filipino diplomat, Naderev Sano, was getting ready to lead his country's negotiations in the UN climate talks in Warsaw, Poland. Yeb, as he is known, is a scientist and head of his country's national climate commission and had flown out of Manila just hours before the vastness of Haiyan had become apparent.

By Monday morning, Sano knew that the Philippines had been struck by possibly the strongest storm ever measured, killing many thousands of people and making millions homeless. He took the floor and, in some trepidation in front of the delegates of 190 countries, gave an extraordinary, passionate speech in which he clearly linked super typhoon Haiyan to manmade climate change and urged the world to wake up to the reality of what he said was happening from latin America to south east Asia and the US. He lambasted the rich countries, and dared climate change deniers to go to his country to see for themselves what was happening.

When he sat down, sobbing, he was given a standing ovation.

This was not just diplomatic theatricals or righteous grandstanding by a developing-country diplomat about the snail-like speed of the climate talks, which have dragged on for years and are not likely to conclude until 2015. What few people in Warsaw knew until Sano had nearly finished his speech was that even as he was addressing the UN, his brother was digging people out of the rubble of the ruined city ofTacloban and he and his family still did not know the fate of other relatives.

Normally stone-hearted diplomats broke down, and Sano, who calls himself a "revolutionary" and a "philosopher" on Twitter [@yebsano], said later he would go on hunger strike for the whole of the two-week meeting. In the last 24 hours he has been joined by 30 activists.

Just as significantly, his speech has reopened the growing debate about whether the extreme weather events seen around the world over the past few years, including Hurricane Sandy, the melting of the Arctic sea ice and heatwaves in the US, Russia and Australia, can be attributed to manmade climate change. If they can, the argument goes, then the urgency of addressing the problem becomes incontrovertible; if it doesn't, then it allows countries to continue delaying action or reducing their commitments.

Logic, at least, suggests a clear link between Haiyan and a warming world. Storms receive their energy from the ocean and the warming oceans that we can expect from global warming should therefore make superstorms such as Haiyan more likely. New research suggests that the Pacific is, indeed, warming – possibly at its fastest rate in 10,000 years. If the extra heat stored in the oceans is released into the atmosphere, then the severity of storms will inevitably increase. In short, a warmer world will probably feature more extreme weather.

This week, atmospheric scientists were clear. "Typhoons, hurricanes and all tropical storms draw their vast energy from the warmth of the sea. We know sea-surface temperatures are warming pretty much around the planet, so that's a pretty direct influence of climate change on the nature of the storm," said Will Steffen, director of the Australian National University (ANU) climate change institute.

"The current consensus is that climate change is not making the risk of hurricanes any greater, but there are physical arguments and evidence that there is a risk of more intense hurricanes," says Myles Allen, head of the climate dynamics group at the University of Oxford.

The consensus of climate scientists is increasingly that super storms will become more frequent. According to a recent special report by the Intergovernmental panel on climate change: "The average tropical cyclone maximum wind speed is likely to increase, but the global frequency of tropical cyclones is likely to decrease or remain unchanged."

In September, the IPCC's fifth assessment stated, more cautiously: "Time series of cyclone indices such as power dissipation, an aggregate compound of tropical cyclone frequency, duration, and intensity that measures total wind energy by tropical cyclones, show upward trends in the North Atlantic and weaker upward trends in the western North Pacific since the late 1970s, but interpretation of longer-term trends is again constrained by data quality concerns."

In other words, the best science says there is some evidence that storm intensity has already increased, at least in the North Atlantic, but there's not enough data to say categorically that any particular weather event can be linked to climate change.

But the science is moving on quickly and it is now possible, with new modelling methods, to quantify and attribute the changed odds of any given event happening. "Because of the random nature of weather, it had been assumed until recently that no single event can be attributed to climate change. However, with new research methods and better quality data, scientists are increasingly able to connect the dots between extreme weather events and climate change," says James Bradbury,formerly a researcher with the World Resources Institute in Washington and now with the US department of energy.

"For example, one can quantify the odds of a typical heatwave happening and estimate how much a warmer world would load the dice toward the more frequent occurrence of a similar event. Or, to understand the causes of melting sea-ice or severe drought, researchers can use sophisticated climate models to help identify – and potentially isolate – various factors that could individually contribute or dynamically interact to influence climate conditions in a particular region," he says.

Evidence that climate change makes heatwaves, superstorms and droughts far more likely is growing. Earlier this year, scientists at the US National Oceanic and Atmospheric Administration (NOAA), the UK's Met Office, and the research teams from 16 other global institutions tried to calculate how much climate change had possibly influenced 12 extreme weather events that occurred in 2012. By no means all could be linked, they concluded, but they agreed that it had helped raise the temperatures during the run of 100F (37.7C) days in last year's US heatwave, and was behind the record loss of Arctic sea ice and the storm surge of hurricane Sandy, plus several other extremes. They were less certain about Britain's wet summer and the drought in Spain.

"Determining the causes of extreme events remains challenging," says Thomas R Karl, director of the national climate data centre. Allen, whose work has shown that global warming tripled the odds of the severe 2010 Russian heatwave and tripled the risk of the widespread flooding in England in 2000, says extreme weather can be linked to climate change given enough computer time. He says the influence of climate change on typhoon Haiyan could be calculated in future: "If we used the same tools as are used now to make seasonal weather forecasts, there would be a straightforward answer."

A 2013 study by MIT's Prof Kerry Emmanuel found that the most intense cyclones – category 3 to 5 – will increase with climate change and also found that "increases in tropical cyclones are most prominent in the western North Pacific", ie where typhoon Haiyan struck.
Ordinary people have less trouble untangling climate change from natural events. Talk to farmers in the Philippines, Nepal, south east Asia, Latin America, much of Africa and Latin America, and most will say that they are seeing more extreme storms, unseasonal rains, and more droughts and heatwaves. Their observations are not "peer-reviewed" by scientists, but their memory is usually good, and invariably supports national records.

The Philippines has been particularly hard hit by extreme events, being the first land mass that typhoons encounter on their usual track westwards from the mid Pacific. Haiyan was the third superstorm to strike the archipelago in a year, coming after seven major typhoons in October alone. Typhoon Trami caused massive flooding on the island of Luzon in August, while Bopha killed around 2,000 people in December last year.

Moreover, the Philippine government's raw statistics suggest the region's typhoons are getting stronger. From 1947 to 1960, the strongest to hit the country was Amy in December 1951, with a highest wind speed recorded at 240kph in Cebu. From 1961 to 1980, the highest wind speed recorded was 275kph in October 1970. In the past 13 years, the highest wind speed has soared to 320kph, recorded by Reming in November to December 2006. "Menacingly, the Philippine typhoons are getting stronger and stronger. If this is due to climate change, we'd better be prepared for even stronger ones in the future," says Romulo Virola, head of the government's national statistics board.

What is certain is that extreme weather events are on the rise globally and that greenhouse gas emissions are rising inexorably. The US alone has experienced 25 extreme weather events since 2011 that each caused more than $1bn in damages. A new report by the Norwegian met office shows that precipitation in Europe has become more severe and more frequent, that winter rainfall has decreased over southern Europe and the Middle East and that there are more and longer heatwaves and fewer extremely cold days and nights.

The evidence is overwhelming that climate change is happening in developing countries, says Oxfam, which works in most of the world's most vulnerable nations. "In 2012 the drought in Russia cut the grain harvest by nearly 25%, in Pakistan the devastating 2010 flood destroyed over 570,000 hectares of crop land and affected more than 20m people. The 2011 drought in East Africa affected over 13 million people and led to a famine in Somalia," says a recent Oxfam report.

According to NOAA, July 2013 marked the 341st consecutive month with a global temperature above the 20th-century average. Thomas Karl, director of NOAA's climate office said: "We believe there is an important human component explaining these record-breaking temperatures, and that's the increase of greenhouse gases in the atmosphere."

Extreme weather killed 530,000 people between 1993 and 2012 and caused more than $2.5tn of damage, according to an annual risk report published on Tuesday by Germanwatch, a thinktank partly funded by the German government. The Philippines was rated second most affected country after Haiti, which lost 9.5% of its economy, just above Pakistan, which was hit by immense floods.

Sano, now on hunger strike, called for a redefinition of "disaster". "We must stop calling events like these as natural disasters," he told the UN. "It is not natural when science already tells us that global warming will induce more intense storms. It is not natural when the human species has already profoundly changed the climate."

Damian Carrington is the head of environment at the Guardian.

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