You’ve probably noticed there’s been some weird stuff going on with the weather lately.
The sheer amount of different extreme weather events going on simultaneously around the world means this could be the winter when climate change becomes ‘real’ our minds, after more than two decades of scientists telling us what its impacts would be.
The recent IPCC AR 5 report concluded the climate is changing and there is a 95% certainty that it is caused by our actions — specifically the burning of fossil fuels, deforestation, and land use change.
But the World Meteorological Organization (WMO) told Energydesk “No single weather episode can prove or disprove global climate change.” Right, and of course many complicated and interrelated variables are in play, of which climate change might only be one factor.
And yes, and there are problems with attributing specific weather to climate change until more sophisticated reverse modeling is possible — an issue examined in a 2013 modeling paper identifying the contribution of climate change for some major flooding and storm events in 2012.
But that does not mean the question should not be asked. As Bob Ward from Grantham Research Institute on Climate Change and the Environment at the London School of Economics told Energydesk:
“The right question is not ‘was it caused by climate change?’ But ‘what impact has climate change had on it?’” He added: “It would be unlikely an almost 1 degree increase in global temperature would have no part to play in extreme weather events.”
What Ward and a group of scientists around the world seem to be saying is that the weather events this winter fit into weather patterns and trends that are consistent with the basic physics of climate change.
For instance, the WMO said: “We do expect to see an increase in extreme heat and precipitation. Already dry regions are expected to become drier and wet ones wetter under IPCC scenarios.”
Energydesk took a look at the most recent evidence on the links between climate change and the types of events we’ve experienced this winter and attempted to unpack how strong these are.
1. Australia’s heatwaves
Last year was Australia’s hottest on record. Temperatures were 1.2 degrees above the average. The country’s Bureau of Meteorology had to add a new color to its maps to represent new extremes in heat.
In December 2013 extreme heat developed over southern, central and eastern Australia, with especially high temperatures in the Australian interior, according to the bureau.
What does this mean for people?
A litany of issues: 100 blazes burning in South Australia, Victoria, and New South Wales (see above bushfire pic); New South Wales and Queensland are suffering drought; heart attacks surged 300% during the heatwave; a spike in deaths in Victoria; blackouts; the Australian Open had to stop play after tennis players collapsed.
What does the science say about links between heatwaves and climate change?
Essentially, the climate in Australia has warmed by about a degree since 1950, and the off-the-charts heatwaves of 2013 are in line with this trend, say government meterologists. Average temperatures are projected to be one to five degrees C higher by 2070.
The link between climate change and record heatwaves is clear, according to Australian scientists at the Climate Council.
The council also says climate change is increasing the risk of bushfires.
Peter Stott, head of climate monitoring at the UK Meteorological Office Hadley Centre told the Financial Times: “Rising temperatures in Australia are a signal of climate change that has emerged very clearly from recent analysis. Last year’s temperatures were a long way outside the envelope of variability that we would expect in the absence of climate change.”
Where else in the world?
Argentina has also witnessed one of the worst heatwaves on record at the end of December, according to the WMO. Extreme warmth settled over Russia towards the end of 2013, according to NOAA. Droughts in California are the worst in decades.
2. UK flooding & storms
The UK has been battered by one storm after another since the start of December, with a series of storms tracking in off the Atlantic bringing strong winds and heavy rain.
According to the MET office December and January’s rainfall was “one of, if not the most, exceptional periods of winter rainfall in the last 248 years”.
PM David Cameron not only put his wellies on for a photo op but said he“strongly suspects” the climate change is causing more “abnormal weather events” such as the floods the UK has been seeing this winter. Even Princes William and Harry have been lugging sandbags.
The British Geological Survey warned that floods could last for months in some areas.
What does this mean for people?
Nearly 6,000 homes flooded across the UK, tens of thousands without electricity, rail networks disrupted, cost of the cleanup could be £1bn to £3bn depending on duration.
What does the science say about the link with the flooding and climate change?
It doesn’t look like a coincidence that four of the five wettest years recorded in the UK have happened since 2000, at the same time as have also had the seven warmest years. As the Met Office pointed out in its recent report, there is increasing evidence showing heavy rainfall is becoming heavier.
They say this is consistent with what you’d expect from basic physics; the astmosphere in a warmer world holds more vater vapour. That means more intense downpours.
The Met office also linked the UK’s storminess with an erratic jet stream, the belt of strong winds circling the planet. The North Atlantic jet stream, which blows in storms from the west towards the UK, has been 30% stronger than normal. Scientists believe this is linked to exceptional wind patterns in the stratosphere.
This whole process has been driven by higher than normal ocean temperatures in the West Pacific, most probably linked to climate change.
Professor Myles Allen, University of Oxford, said: “There are simple physical reasons, supported by computer modelling of similar events back in the 2000s, to suspect that human-induced warming of the climate system has increased the risk of the kind of heavy rainfall events that are playing a major role in these floods.”
Where else in the world?
In December Brazil saw torrential rains in which at least 22 people were killed and tens of thousands made homeless.
3. US & Canada cold snap
Extremely cold weather has plagued the the US and Canada over the past couple of months. Even the Niagra Falls froze (see above pic). The pattern established in December has continued through February, says the WMO.
In an unprecedented move, the White House released a video explaining how the freezing spell was linked to climate change. The White House also organised a Google+ hangout on the polar vortex phenomenon.
What does it mean for people?
What does the science say about the link with the cold snap and climate change?
It might seem counter-intuitive, but the cold snap is likely to be linked to climate change.
A split between the Pacific and Atlantic jet streams — with its root in warming ocean temperatures in the Pacific — has resulted in colder air being carried south over North America.
Warming sea ice has also been involved in the frigid weather according to recent studies. It has been implicated in a huge meander in the jet stream over North America resulting in warm weather over Alaska and the west of the US while the rest of the US and Canada freezes.
Another theory about melting Arctic ice driving weather changes is the ‘Arctic Paradox‘ or ‘Warm Arctic – Cold Continent‘ pattern. Research suggests that as more Arctic sea ice is melting in the summer, the Arctic Ocean warms and radiates heat back into the atmosphere in winter.
This disturbs the Polar Vortex — essentially a pattern of strong winds circulating around a low-pressure system that normally sits over the Arctic in the winter — bringing relatively mild conditions to the Arctic while places far to the south bear the brunt of freezing winds. The Polar Vortex is stronger than normal, with increased winds around the vortex. The vortex has distorted, and its core has extended down over Canada.
In the White House video, President Obama’s science and technology advisor, Dr John Holdren, said:
“A growing body of evidence suggests that the kind of extreme cold experienced by the United States is a pattern we can expect to see with increasing frequency as global warming continues… I believe the odds are that we can expect as a result of global warming to see more of this pattern of extreme cold in the mid latitudes and some extreme warm in the far north.”
4. Supertyphoon Haiyan
Hitting the Philippines with winds of 310km/h, typhoon Haiyan was the strongest tropical cyclone to make landfall in recorded history. The devastation in coastal areas such as Tacloban was principally caused by a six meter storm surge that carried away even concrete buildings.
What did it mean for people?
Haiyan killed 5,000 people, flattened islands, and damaged more than a million houses. It was a humanitarian disaster.
What does the science say about the link with supertyphoon and climate change?
There’s a lot of discussion among scientists over whether storms are getting worse in a warming world. Meteorologists say it’s impossible to blame climate change for individual storms.
Scientists think its plausible that tropical storm activity will rise as the planet warms, on balance. This is despite the effects of increasingly strong ‘shearing’ winds to prevent the formation of storms or dissipate them.
There is some evidence linking climate change to increasing storm intensity over the past three decades, especially in north Atlantic where data is available, as described in the IPCC 5 report. But in other places, such as the northwest Pacific basin, our knowledge is more sketchy because of a lack of data.
One aspect of Haiyan’s devastation that could be linked to climate change is the fact that rising sea levels, caused by global warming, contributed to the volume of water of the storm surge.
Julian Heming, a tropical storm prediction scientist at the Met Office told The Telegraph: “We need to look at long-term climate models before we can be certain. But the indications are that the frequency of the storms may decrease — but their intensity will increase.”
Where else in the world?
Climate change was linked to Hurricane Sandy, which hit the east coast of the US in October 2013. The storm was exacerbated by a ‘blocking high’ of cold air coming down from Canada, a phenomenon linked to global warming by climate scientists.