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The new normal

  • 14 Sep 2011, 00:00
  • Neil Roberts

US wildfires. Photo: © charentelibre

"All weather events are now influenced by climate change because all weather now develops in a different environment than before."

With this great line Dr. Richard Somerville from the new Climate Communication project summarised the position now taken by many climate scientists, traditionally wary of linking extreme weather events with climate change.

Somerville, professor Emeritus of Scripps Institution of Oceanography and science director of Climate Communication, went on:

"Some types of extreme weather events are becoming more frequent and or severe due to climate change, heat waves, heavy rain, floods, and droughts among them. Climate change is increasing the odds that extreme weather will occur."

Climate Communication labels itself as a "non-profit science and outreach project". It was launched last month by a group of respected climate scientists and science communication staff and is funded by the Rockerfeller Brothers Fund and the ClimateWorks Foundation It is headed by Director Susan Joy Hassol, a climate change communicator, analyst, and author; Dr Somerville is the project's science director. Its science advisers include Jeff Masters of the Weather Underground, Bob Corell, chair of the Arctic Climate Impact Assessment, and Greg Holland, chair of the Regional Climate Prediction Program at the National Center for Atmospheric Research. Hassol has outlined more about the project in a guest post at Climate Progress.

With extreme weather events hardly out of the news in recent weeks, Climate Communication's press conference last week attracted attention. Their overview of the subject makes the point:   

"Recent weather events such as deadly heat waves and devastating floods have sparked popular interest in understanding the role of global warming in driving extreme weather. These events are part of a new pattern of more extreme weather across the globe, shaped in part by human-induced climate change."

They go on:

"Rigorous analyses have shown that natural variability alone cannot explain the observed long-term trends of changing extremes in temperature and precipitation.

"In contrast, the observed trends fit well with our understanding of how climate change drives changes in weather. Computer models of the climate that include both natural forces as well as human influences are consistent with observed global trends in heat waves, warm days and nights, and frost days over the last four decades. Human influence has also been shown to have contributed to the increase of heavy precipitation over the Northern Hemisphere.

"Extreme weather events do not have a single cause but instead have various possible contributing factors - and human-induced climate change is now one of those factors."

Kelly Rigg, of the Global Campaign for Climate Action, writing at Huff Post recently argued:

"It's time to change the terms of this fruitless debate. When asked whether an extreme weather event is caused by climate change, scientists should reframe the debate by rephrasing the question: "Are more events like this what you would expect in a warming world?" The answer would be a resounding "yes.""

This discussion has been particularly live in the US recently. There were the hurricanes - Irene and Katia -  and the drought and wildfires across Texas and other US states, that have all added to the United States' sense of " meteorological misery".

However, as Jules Boykoff at Comment is Free wrote last week:

"But recent record-breaking "meteorological misery" from coast to coast is making it clear that severe weather may well be the new normal. Weather is getting more extreme and this, scientists tell us, has a lot to do with climate change. Meanwhile, inside the Beltway and among mainstream media, there's virtually no public debate about the likelihood we're already paying the high price of climate change."

Meanwhile, in Pakistan five million people have been affected by floods in Baluchistan and Sindh. Climate Signals reported "900 villages have been submerged and about 100,000 homes have been completely destroyed."

As a Reuters piece noted last week, scientists have traditionally been cautious about linking extreme weather events with climate change. It is not possible to directly link any particular event with the effects of the changing climate - but as this from Climate Centralshows, scientists are becoming more willing to say that climate change is making the extreme weather we are experiencing now more likely:

"Seager [Columbia University Lamont Doherty Earth Observatory] climate change, driven by increasing amounts of greenhouse gases in our atmosphere, is tilting the scales in favor of future droughts that may look like this one."

New research from Boston University, published in Climate Change Letters journal, has attracted attention. The research estimated the impact near-term increases in global temperatures will have on summertime temperatures in the U.S. and around the globe and concluded that:

"substantial fractions of the globe could experience seasonal-mean temperature extremes with high regularity, even if the global-mean temperature increase remains below the 2°C target."

Monday's Guardian leader picked up on that same research. The paper quoted climate secretary Chris Huhne's warning that we face "unprecedented environmental and geopolitical catastrophe". Huhne, the Guardian says, is right to issue his warning. But, echoing the points made by Boycoff: "There is no great evidence that fellow politicians are listening very intently."

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