Michael Mann: How Close Are We to 'Dangerous' Planetary Warming?
In the wake of the COP 21 UN climate summit in Paris, a number of important questions still remain unanswered. Take for example the commitment reached by the 197 participating nations to limit warming below the "dangerous" level of 2C relative to pre-industrial time (neglecting for the time being the aspirational goal of a substantially lower 1.5C limit acknowledged in recognition of the danger posed to low-lying island nations). The question immediately arises: How much time do we have until we reach the danger zone? How close are we to the 2C warming limit?
It has been widely reported that 2015 will be the first year where temperatures climbed to 1C above the pre-industrial. That might make it seem like we've got quite a ways to go until we breach the 2C limit. But the claim is wrong. We exceeded 1C warming more than a decade ago. The problem is that here, and elsewhere, an inappropriate baseline has been invoked for defining the "pre-industrial." The warming was measured relative to the average over the latter half of the 19th century (1850-1900). In other words, the base year implicitly used to define "pre-industrial" conditions is 1875, the mid-point of that interval. Yet the industrial revolution and the rise in atmospheric CO2 concentrations associated with it, began more than a century earlier.
Unfortunately, even the Intergovernmental Panel on Climate Change (IPCC) has fallen victim to this problematic convention in their latest (5th) assessment report. The key graphic (Fig. 1 below) in the Summary for Policy Makers ("SPM") of the report measures net anthropogenic (i.e. human-generated) carbon emissions and the resulting warming that can be expected. Both the emissions and warming and measured relative to an 1870 baseline.
The various future emissions scenarios are called "RCP"s (for "Representative Concentration Pathways") and they reflect varying assumptions regarding our future efforts to limit carbon emissions. The "RCP 2.6" scenario (dark blue), the most aggressive of the scenarios (from the standpoint of ramping down carbon emissions), corresponds to limiting net carbon emissions to about 3000 Gigatons (3 trillion tons) of CO2. We've already burned through about 2,000 Gigatons, i.e. we have expended two thirds of our apparent "carbon budget."
Achieving those limits in emissions would in turn limit maximum atmospheric CO2 concentrations to just under 450 parts per million ("ppm"). Pre-industrial levels were about 280 ppm. Current levels are just above 400 ppm and increasing by about 2.1 ppm per year. At that rate, we'll reach 450 ppm in a little over two decades. So obviously we need to reduce our carbon emissions rather rapidly if we are to avoid crossing the 450 ppm threshold.
The IPCC graphic suggests that keeping net CO2 emissions below 3 trillion tons—and thereby stabilizing maximum CO2 concentrations below 450 ppm—would likely keep warming below the "dangerous" 2C limit. Unfortunately, that conclusion is overly optimistic because, once again, it relies on the use of an artificially warm, too-recent baseline for defining the pre-industrial period.
To better understand the problem, consider this graph (Fig. 2 below) from an article my colleagues and I published in the American Meteorological Society's Journal of Climate back in 2013.
Source: Schurer et al (2013)
The graph shows the warming of the Northern Hemisphere (in degrees C) due to human-generated greenhouse gases ("GHG") alone, as estimated by the various climate models used in the IPCC 5th assessment report (the black curve—the "multimodel mean" is the average over all of the climate model simulations that were done). The graph has been annotated to indicate the warming observed by 1800 and 1900. It is evident that roughly 0.3C greenhouse warming had already taken place by 1900, and roughly 0.2C warming by 1870. While that might seem like a minor amount of warming, it has significant implications for the challenge we face in stabilizing warming below 2C, let alone 1.5C, as we shall see below.
A "trash tsunami" has washed ashore on the beaches of Honduras, endangering both wildlife and the local economy.
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More long-finned pilot whales were found stranded today on beaches in Tasmania, Australia. About 500 whales have become stranded, including at least 380 that have died, the AP reported. It is the largest mass stranding in Australia's recorded history.
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By Harry Kretchmer
By 2030, almost a third of all the energy consumed in the European Union must come from renewable sources, according to binding targets agreed in 2018. Sweden is helping lead the way.
Sweden is a world leader in renewable energy consumption. Swedish Institute/World Bank
Naturally Warm<p>54% of Sweden's power comes from renewables, and is helped by its geography. With plenty of moving water and 63% forest cover, it's no surprise the <a href="https://sweden.se/nature/energy-use-in-sweden/#" target="_blank">two largest renewable power sources</a> are hydropower and biomass. And that biomass is helping support a local energy boom.</p><p>Heating is a key use of energy in a cold country like Sweden. In recent decades, as fuel oil taxes have increased, the country's power companies have turned to renewables, like biomass, to fuel local 'district heating' plants.</p><p>In Sweden these trace their <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank">origins back to 1948</a>, when a power station's excess heat was first used to heat nearby buildings: steam is <a href="https://www.sciencedirect.com/topics/engineering/district-heating-system" target="_blank">forced along a network of pipes</a> to wherever it's needed. Today, there are around 500 district heating systems across the country, from major cities to small villages, providing heat to homes and businesses.</p><p>District heating used to be fueled mainly from the <a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140" target="_blank">by-products of power plants</a>, waste-to-energy plants and industrial processes. These days, however, Sweden is bringing more renewable sources into the mix. And as a result of competition, this localized form of power is now the country's<a href="https://www.sciencedirect.com/science/article/pii/S0360544217304140#fig3" target="_blank" rel="noopener noreferrer"> home-heating market leader.</a></p>
Sweden is using smart grids to turn buildings into energy producers. Huang et al/Elsevier
Energy ‘Prosumers’<p>But Sweden doesn't stop at village-level heating solutions. Its new breed of energy-generation takes hyper-local to the next level.</p><p>One example is in the city of Ludivika where 1970s flats <a href="https://www.buildup.eu/sites/default/files/content/transforming-a-residential-building-cluster-into-electricity-prosumers-in-sweden.pdf" target="_blank">have recently been retrofitted with the latest smart energy technology</a>.</p><p>48 family apartments spread across 3 buildings have been given photovoltaic solar panels, thermal energy storage and heat pump systems. A micro energy grid connects it all, and helps charge electric cars overnight.</p><p>The result is a cluster of 'prosumer' buildings, producing rather than consuming enough power for 77% of residents' needs. With <a href="http://www.diva-portal.org/smash/get/diva2:1232060/FULLTEXT01.pdf" target="_blank" rel="noopener noreferrer">high levels of smart meter usage</a>, it's a model that looks set to spread across Sweden.</p>
<div id="d7bf9" class="rm-shortcode" data-rm-shortcode-id="8757b138d5570bec9d6aad18074a429a"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1273556364263071744" data-partner="rebelmouse"><div style="margin:1em 0">Read more about Western Harbour and book a visit: https://t.co/ujSmVs9rNK 🏡🌳🌊 https://t.co/C5PuPziqIM</div> — Smart City Sweden (@Smart City Sweden)<a href="https://twitter.com/SmartCitySweden/statuses/1273556364263071744">1592474473.0</a></blockquote></div>
Scaling Up<p>A recent development by E.ON in Hyllie, a district on the outskirts of Malmö, southern Sweden, <a href="https://www.eonenergy.com/blog/2019/February/sweden-smart-city" target="_blank">has scaled up the smart grid principle</a>. Energy generation comes from local wind, solar, biomass and waste sources.</p><p>Smart grids then balance the power, react to the weather, deploying extra power when it's colder or putting excess into battery storage when it's warm. The system is not only more efficient, but bills have fallen.</p><p>Smart energy developments like those in Hyllie, Ludivika, and renewable-driven district heating, offer a radical alternative to the centralized energy systems many countries rely on today.</p><p>The EU's leaders have a challenge: how to generate 32% of energy from renewables by 2030. Sweden offers a vision of how technology and local solutions can turn a goal into a reality.</p>
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By Jessica Corbett
In another win for climate campaigners, leaders of 12 major cities around the world — collectively home to about 36 million people — committed Tuesday to divesting from fossil fuel companies and investing in a green, just recovery from the ongoing coronavirus pandemic.
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