11 December 2015, The Conversation, Climate and the rise and fall of civilizations: a lesson from the past. 2015 will likely be the hottest year on record, beating the previous record set only in 2014. It is also likely to be the first year the global average temperature reaches 1℃ above pre-industrial temperatures (measured from 1880-1899). Global warming is raising temperatures, and this year’s El Niño has pushed temperatures higher still. Although 2015 is unusually hot, 1℃ symbolically marks the halfway point to 2℃, widely considered to be the threshold of “dangerous” climate change. In fact an additional 0.5-1℃ is actually masked by sulphur aerosols which we have added to the atmosphere alongside greenhouse gases. A temperature level of 1℃ (above pre-industrial levels) is similar to or warmer than the peak temperatures of the early Holocene epoch approximately 8,000-7,200 years ago. Studies of the early Holocene provide clues to what was such a world like. The climate roller-coaster The last ice age (or Last Glacial Maximum) peaked around 26,000 years ago. The earth warmed over the coming millennia, driven by an increase in radiation from the sun due to changes in the earth’s orbit (the Milankovic cycles) amplified by CO₂ released from warming water, which further warmed the atmosphere. But even as the earth warmed it was interrupted by cooler periods known as “stadials”. These were caused by melt water from melting ice sheets which cool large regions of the ocean. Marked climate variability and extreme weather events during the early Holocene retarded development of sustainable agriculture. Sparse human settlements existed about 12,000 – 11,000 years ago. The flourishing of human civilisation from about 10,000 years ago, and in particular from 7,000 years ago, critically depended on stabilisation of climate conditions which allowed planting and harvesting of seed and growing of crops, facilitating growth of villages and towns and thereby of civilisation. Read More here
9 December 2015, Climate News Network, Ice melt highlights Inuit plight. COP21: As Arctic peoples’ leaders appeal for unity to halt global warming, scientists report that Greenland’s glaciers are now melting at a speed not seen since the last Ice Age. The glaciers of Greenland are retreating two to three times faster now than at any time since the last Ice Age ended 9,500 years ago, according to new research. The news comes as indigenous peoples from the northern polar region staged anArctic Day at the COP21 climate change summit in Paris. Leaders of Greenland peoples, the Nunavut region of Canada and the Inuit Circumpolar Council appealed to the governments of the world to unite to dramatically reduce greenhouse gas emissions and keep global warming to between 1.5˚C and 2˚C. That is because the Arctic is now warming faster than almost anywhere else on Earth, and both human settlements and natural ecosystems are vulnerable. That the Greenland glaciers are in retreat is itself not news. Satellite data and measurements on the ground have repeatedly confirmed the retreat of the glaciers, the loss of ice and the acceleration of flow. The Jakobshavn Isbrae glacier has even reached a speed of 17 kilometres a year. Sediment cores But US scientists report in Climate of the Past journal that the present rate of loss is without precedent. Read More here