UXBRIDGE - Human-induced heating of the planet has already made rainfall more intense, leading to more severe floods, researchers announced Wednesday.
Two new studies document significant impacts with just a fraction of the heating yet to come from the burning of fossil fuels. Fortunately, another new report shows the world can end its addiction to climate-wrecking fossil-fuel energy by 2050.
"Warmer air contains more moisture and leads to more extreme precipitation," said Francis Zwiers of the University of Victoria.
Extreme precipitation and flooding over the entire northern hemisphere increased by seven percent between 1951 and 1999 as a result of anthropogenic global warming. That represents a "substantial change", Zwiers told IPS, and more than twice the increase projected by climate modeling.
Zwiers and Xuebin Zhang of Environment Canada used observations from over 6,000 weather stations to measure the impact of climate warming on the intensity of extreme precipitation for the first time. The study was published Wednesday in the journal Nature.
The planet is currently 0.8 degrees C hotter from the burning of fossil fuels. However, global temperatures had not yet started to increase in 1951, the first year of rainfall data Zwiers and Xuebin examined. By 1999, global temperatures had climbed by about 0.6 degrees C. The average temperature increase over that 50-year period is relatively small compared to the present but major impacts have been documented in terms of storm and flood damage even with this small increase in temperatures.
This suggests that the Earth's climatic system may be more sensitive to small temperature increases than previously believed.
The global costs of extreme weather events shot up from less than five billion dollars a year during the 1950s to 45 billion dollars a year during the 1990s, according to Munich Re, a major reinsurance company in Germany. Not all of this increase is due to climate change. Some is due to population and infrastructure growth and better disaster reporting. However, the number of significant floods has tripled in the past 30 years.
Those costs came during a time when the planet was cooler than present - a period of "relatively weak anthropogenic forcing", Zwiers said. But as temperatures climbed, there was a sharp increase in intense rainfall events during the 1990s, suggesting an acceleration in flooding and damaging rainfall. Zwiers said it is too soon to know if the 1990s increase represents a new trend.
Global temperatures are guaranteed to increase further from today's 0.8 degrees C to at least 1.0 degree C by 2020. This will boost the amount of water vapour and heat in the atmosphere, which are the fuel for even more and harder rainfall events.
Scientists have long known extreme events would increase with a hotter planet but have maintained that a single flood or storm could not be explicitly linked to climate change. Now another study published Wednesday in Nature lays odds they've found the "smoking gun" behind Britain's severe flooding in 2000.
During the fall of 2000, the UK experienced some of its most damaging floods and wettest weather since the first records began in 1766. Using the distributed computing power from thousands of personal computers around the world, researchers at Oxford University and others determined that human emissions of greenhouse gases had more than doubled the odds of the devastating 2000 flood.
"We simulated a parallel world in which there were no greenhouse gas emissions," said lead researcher Pardeep Pall of Oxford University.
Thousand of computer simulations were tested against reality and the results revealed that climate change more than doubled the odds of the 2000 flooding, Pall said at a press conference.
"This study was 20 times more demanding than anything we're tried before. It is not easy to precisely say what caused what when it comes to a single weather event," added Myles Allen of Oxford University.
The UK Met Office is developing new methods for assessing extreme weather events and determining the factors that caused them in hopes of improving predictions. In future, the Met Office may be able to predict such events and explain why they happened, said Allen.
With human-induced heating of the planet expected by many to reach at least 2.4 degrees C in the coming decades, extreme events of the recent past will seem very tame indeed. However, this calamitous future can be avoided with a rapid transition to a renewable global energy system.
A detailed new study demonstrates that 95 percent of global energy needs can be meet with renewables utilising today's technologies alone.
The Energy Report by Ecofys, a leading energy consulting firm in the Netherlands, is the first to show that 95 percent of all energy can be renewable by 2050, while offering comfortable lifestyles for a growing global population and allowing a tripling of the global economy.
"We can do this by using and improving the technologies that are already at hand," said Manon Janssen, CEO of Ecofys. "It is a business opportunity, as much as it is a technological challenge."
Ecofys spent two years preparing the report in partnership with the World Wildlife Fund.
Paramount will be major increases in energy efficiency in all sectors so that by 2050 energy use is 15 percent less than the energy use in 2005. And this is all possible with existing technology, the report noted. Emissions from burning fossil fuels for energy will fall more than 80 percent by 2050, offering a real chance of keeping global temperatures below 2 degrees C, the report said.
While the transition will be costly, the savings from lower energy use will amount to a five- to six-trillion-dollar "windfall" for humanity by 2050.
The move to renewable energy is already well underway in places like California, where the cost of generating solar energy is now as cheap as fossil fuels, said Justin Gerdes, a California journalist specialising in energy issues.
"Renewables already benefit from lower upfront costs to install - especially onshore wind - compared to huge one- gigawatt fossil fuel or nuclear plants," Gerdes said. "And, then, of course, the renewables have no cost for fuel."
And this is happening in the U.S., where climate change is a non-issue politically and there is no price or cap on carbon emissions.
"In short, this can happen," Gerdes said.