This week The Climate Show brings you an all news special. We have wet summers for Europe, permafrost warming delivering a methane kick, La Niña driving floods that make sea level fall, a glacier calving in Antarctica, mammoths and sabre tooth tigers — all delivered with Glenn and Gareth’s inimitable panache (!).
Arctic sea ice became a recurrent feature on planet Earth around 47 million years ago. Since the start of the current ice age, about 2.5 million years ago, the Arctic Ocean has been completely covered with sea ice. Only during interglacials, like the one we are in now, does some of the sea ice melt during summer, when the top of the planet is oriented a bit more towards the Sun and receives large amounts of sunlight for several summer months. Even then, when winter starts, the ice-free portion of the Arctic Ocean freezes over again with a new layer of sea ice.
Since the dawn of human civilisation, 5000 to 8000 years ago, this annual ebb and flow of melting and freezing Arctic sea ice has been more or less consistent. There were periods when more ice melted during summer, and periods when less melted. However, a radical shift has occurred in recent times.
Ever since satellites allowed a detailed view of the Arctic and its ice, a pronounced decrease in summer sea ice cover has been observed (with this year setting a new record low). When the IPCC released its Fourth Assessment Report in 2007, it was generally thought that the Arctic could become ice-free somewhere near the end of this century. But changes in the Arctic have progressed at such speed that most experts now think 2030 might see an ice-free Arctic for the first time. Some say it could even happen this decade.
What makes this event significant, is the role Arctic sea ice plays as a reflector of solar energy. Ice is white and therefore reflects a large part of incoming sunlight back out to space. But where there is no ice, dark ocean water absorbs most of the sunlight and thus heats up. The less ice there is, the more the water heats up, melting more ice. This feedback has all kinds of consequences for the Arctic region.
The UN Environment Programme’s just released Year Book 2012 includes a report The Benefits of Soil Carbon which looks at the vital role played by soil carbon in regulating climate, water supplies and biodiversity, and maintaining the ecosystem services that we depend on. The report is 15 pages long and well presented for general reading. I thought it well worth drawing attention to. I’ll point to a few of the report’s highlights here, in particular those that relate to climate change.
First, it offers a reminder of how important a carbon storehouse the soil is. The top metre of the world’s soils stores more than three times the amount of carbon held in the atmosphere (approximately 2200 billion tonnes of carbon, two-thirds of it in the form of organic matter). This sequestration gives soils an essential role in climate regulation. However, soils are vulnerable to carbon losses through degradation. They also release greenhouse gases to the atmosphere as a result of accelerated decomposition due to land use change or unsustainable land management practices. Continue reading “The Benefits of Soil Carbon”
The Climate Show returns with a packed show, featuring one of the world’s best known climate scientists, NZ-born, Colorado-based Dr Kevin Trenberth — star of the Climategate “where’s the missing heat” emails. He’s been in New Zealand to visit family (experiencing the Christchurch quake in the process) and to attend a conference, and his comments on the state of our understanding of climate change should not be missed. John Cook of Skeptical Science returns with his new short urls and an explanation of why declines have never been hidden, and Gareth and Glenn muse on Arnie “Governator” Schwarzenegger riding to the rescue of climate science, cryospheric forcing and carbon cycle feedbacks from melting permafrost, and a new paper that suggests that current policies are pointing us towards extremely dangerous climate change. All that and hyperbranched aminosilica too…
Show notes below the fold.
Excellent animation by Leo Murray explaining climate system feedbacks and the potential for us to pass “tipping points” that could make our efforts to reduce emissions completely redundant. More information (including script and references) at wakeupfreakout.org. Hat-tip to Peter “Crock of the Week” Sinclair for finding it…