Global warming is “unequivocal” and humans are turning up the heat — but more slowly since 1998, according to a report from the United Nations Intergovernmental Panel on Climate Change released today.
Each of the last three decades has been warmer at the Earth’s surface than any previous decade since 1850, says the 36-page Summary for Policymakers of the IPCC Working Group’s assessment report, approved today by IPCC member governments in Stockholm. In the Northern Hemisphere, 1983–2012 was “likely” the warmest 30-year period of the last 1400 years.
The atmosphere and oceans have warmed, snow and icecaps diminished, sea levels have risen and concentrations of greenhouse gasses (CO2, methane and nitrous oxide) have increased since 1750 due to human activity, the report concludes.
But the rate of warming over the past 15 years (from 1998 to 2012) is slower than the rate calculated since 1951, according to the assessment. Average global temperatures rose at 0.05 degree Celsius per decade from 1998 through 2012, compared to 0.12 degree per decade from 1951 through 2012. This 15-year slow down in temperature increases, however, does not reflect long-term climate trends, the report says.
Global surface temperature change by the end of the 21st century will likely exceed 1.5 degrees Celsius, relative to 1980 to 1900, in all but the lowest scenarios considered by scientists, and will likely exceed 2 degrees Celsius for the two highest scenarios.
The assessment also says the rate of global sea level rise will “very likely” exceed the rate observed between 1971 and 2012. It attributes this to hotter ocean temperatures and melting glaciers and ice sheets.
Limiting climate change will require “substantial and sustained” GHG reductions, says Thomas Stocker, co-chair of the working group.
Ceres says the IPCC report confirms climate change is affecting businesses’ bottom lines and their strategies.
VF Corporation — one of the world’s largest single purchasers of cotton, whose brands include Lee, Wrangler and The North Face — says much of the world’s cotton comes from areas that are expected to be impacted most by water scarcity and extreme weather such as the Western US, China, Pakistan and India. The IPCC report makes firms’ risks associated with climate change even more clear, says Letitia Webster, VF’s director of global corporate sustainability.
Climate change hurts VF’s outdoor and recreation brands, Webster says: “Whether in mountains or the ocean, our brands and our consumers are feeling the impacts of climate change,” which means less ski-related business for The North Face. The company today signed Ceres’ Climate Declaration, calling on US policymakers to enact climate and clean energy policies that will benefit the economy.