RICHMOND, Va. (WTVR) - After days of record hot weather and extreme heat across the Southwestern U.S. (caused by a stationary high pressure system over a region already experiencing recent years of drought), some scientists are pointing to this event as an example of the kinds of extreme weather events that are becoming more common.
The United Nations released a report Wednesday, July 3 saying the Earth saw "unprecedented high-impact climate extremes" between 2001 and 2010, with every spot on the globe affected in some way. More nations broke temperature records during that decade than in any other decade on record. Almost half the nations on Earth broke 50-year-old records for high temperatures. The report went on to say this is the warmest decade (globally) we've seen over the past century.
Global temperatures have been rising so steeply since the 1980s that Arctic sea ice is now melting twice as fast as it once did. The Arctic is warming faster than any other part of the world.
“Rising concentrations of heat-trapping greenhouse gases are changing our climate, with far-reaching implications for our environment and our oceans, which are absorbing both carbon dioxide and heat,” said Michel Jarraud, the Secretary-General of the World Meteorological Organization (WMO), which produced the report.
The report opens with scientists pointing to human-induced changes. "The rapid changes that have occurred since the middle of the past century, however, have been caused largely by humanity’s emissions of greenhouse gases into the atmosphere. Other human activities also affect the climate system, including emissions of pollutants and other aerosols, and changes to the land surface, such as urbanization and deforestation."
Greenhouse gases are quickly honed in as the biggest contributor to climate change in this report. "According to the WMO Greenhouse Gas Bulletin, global-average atmospheric concentrations of carbon dioxide rose to 389 ppm in 2010 (an increase of 39 per cent compared to pre-industrial times), methane to 808.0 ppb (158 per cent) and nitrous oxide to 323.2 ppb (20 per cent). This changing composition of the atmosphere is causing the global average temperature to rise, which, in turn, exerts a significant influence on the hydrological cycle and leads to other changes in climate and weather patterns."
CLICK HERE to read the full United Nations report.
The report explains that other climate variables like El Nino and La Nina do show a fingerprint on the record.
And as important as it is to look at the long-term trends for the "big picture," you may often wonder why your local, daily experienced temperatures may not seem to "fit" with what is happening globally. Not every day is going to be an "extreme weather day" in your neighborhood. We have to remember that natural climate variability is still happening in the midst of the long-term warming pattern.
The UN report says, though, "Human influence has probably increased the maximum temperatures of the most extreme hot nights and days and the minimum temperatures of cold nights and cold days. It is also more likely than not that human-induced climate change has increased the risk of heatwaves."
What about tropical cyclones? The UN report concludes that more research is needed to determine how long-term global warming is impacting tropical systems. "No clear trend has been found in tropical cyclones and extra-tropical storms at the global level. More complete datasets will be needed in order to perform robust analyses of trends in the frequency and intensity of these hazards." There is also no clear picture yet of how other extreme severe weather events like tornadoes and severe thunderstorms are linked to a warming planet. The best scientific knowledge about the link between climate change and extreme events are for events like heat waves, cold waves, precipitation trends, floods, and droughts.