- What is climate change?
- How has climate changed?
- Are human activities causing climate change?
- How do we expect climate to evolve in the future?
- How are extreme events changing?
- How are sea levels changing?
- What are the impacts of climate change?
- What are the uncertainties and their implications?
- What does science say about options to address climate change?
Sunday, February 15, 2015
Latest information on climate change
Saturday, February 7, 2015
Quantifying the impact of climate change on extreme heat in australia
1. Climate change is making Australia hotter. Hot days are happening more often while heatwaves are becoming hotter, longer and more frequent.
- The annual number of record hot days across Australia has doubled since 1960. Over the past 10 years the number of record hot days has occurred three times more frequently than the number of record cold days.
- The annual occurrence of very hot days across Australia has increased strongly since 1950 and particularly sharply in the last 20 years.
- Over the 1950-2013 period many characteristics of heatwaves have changed across Australia. They are becoming hotter, lasting longer, occurring more often and starting earlier.
- All extreme heat events are now occurring in an atmosphere that is significantly hotter than it was 50 years ago
2. While it has been clear for many years that climate change is a major factor in intensifying heat, recent scientific advances now allow us to understand the extent of the impact on individual extreme events. Climate change has significantly worsened recent extreme heat events in Australia.
- The record hot year of 2013 in Australia was virtually impossible without climate change.
- Climate change tripled the odds that the heatwaves of the 2012/2013 Australian summer would occur as frequently as they did.
- Climate change doubled the odds that the 2012/2013 heatwaves would be as intense as they were.
3. The new research showing the strong influence of climate change on heat events strengthens the case for strong action on climate change.
- Carbon emissions must be reduced rapidly and deeply if the worst of extreme heat in the second half of the century is to be avoided.
- Clean energy technologies are advancing rapidly and international action is ramping up, building momentum towards a decarbonised future.
Sunday, August 24, 2014
'Incredible' rate of polar ice loss alarms scientists
A European satellite has shown ice sheets shrinking at 120 cubic miles a year in Antarctica and Greenland
The planet's two largest ice sheets – in Greenland and Antarctica – are now being depleted at an astonishing rate of 120 cubic miles each year. That is the discovery made by scientists using data from CryoSat-2, the European probe that has been measuring the thickness of Earth's ice sheets and glaciers since it was launched by the European Space Agency in 2010.
Even more alarming, the rate of loss of ice from the two regions has more than doubled since 2009, revealing the dramatic impact that climate change is beginning to have on our world.
The researchers, based at Germany's Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research – used 200m data points across Antarctica and 14.3m across Greenland, all collected by CryoSat, to study how the ice sheets there had changed over the past three years. The satellite carries a high-precision altimeter, which sends out short radar pulses that bounce off the ice surface and then back to the satellite. By measuring the time this takes, the height of the ice beneath the spacecraft can be calculated.
It was found from the average drops in elevation that were detected by CryoSat that Greenland alone is losing about 90 cubic miles a year, while in Antarctica the annual volume loss is about 30 cubic miles. These rates of loss – described as "incredible" by one researcher – are the highest observed since altimetry satellite records began about 20 years ago, and they mean that the ice sheets' annual contribution to sea-level rise has doubled since 2009, say the researchers whose work was published in the journalCryosphere last week.
"We have found that, since 2009, the volume loss in Greenland has increased by a factor of about two, and the West Antarctic ice sheet by a factor of three," said glaciologist Angelika Humbert, one of the study's authors. "Both the West Antarctic ice sheet and the Antarctic peninsula, in the far west, are rapidly losing volume. By contrast, East Antarctica is gaining volume, though at a moderate rate that doesn't compensate for the losses on the other side of the continent."
The researchers say they detected the biggest elevation changes caused by ice loss at the Jakobshavn glacier in Greenland, which was recently found to be shifting ice into the oceans faster than any other ice-sheet glacier, and at Pine Island glacier, which like other glaciers in West Antarctica, has been thinning rapidly in recent years.
The discovery of these losses of ice is particularly striking and represents yet another blow to claims by some climate-change deniers, who argue that the rapid loss of ice in the Arctic currently being observed is being matched by a corresponding increase in Antarctica. CryoSat's measurements show that Antarctica – although considerably colder than the Arctic because of its much higher average elevation – is not gaining ice at all. Indeed, it is – overall – losing considerable volumes, and in the case of West Antarctica is doing so at an alarming rate.
This point was stressed by Mark Drinkwater, the European Space Agency's CryoSat mission scientist. "These results offer a critical new perspective on the recent impact of climate change on large ice sheets. This is particularly evident in parts of the Antarctic peninsula, where some of the more remarkable features add testimony on the impact of sustained peninsula warming at rates several times the global average."
Sunday, June 1, 2014
Australia's past two years the hottest on record, Climate Council says
Thursday, April 17, 2014
Mitigation of Climate Change – Part 3 of the new IPCC report
RealClimate, 17 April 2014
Guest post by Brigitte KnopfGlobal emissions continue to rise further and this is in the first place due to economic growth and to a lesser extent to population growth. To achieve climate protection, fossil power generation without CCS has to be phased out almost entirely by the end of the century. The mitigation of climate change constitutes a major technological and institutional challenge. But: It does not cost the world to save the planet.
The 2-degree limit
For the first time, a detailed analysis was performed of how the 2-degree limit can be kept, based on over 1200 future projections (scenarios) by a variety of different energy-economy computer models. The analysis is not just about the 2-degree guardrail in the strict sense but evaluates the entire space between 1.5 degrees Celsius, a limit demanded by small island states, and a 4-degree world. The scenarios show a variety of pathways, characterized by different costs, risks and co-benefits. The result is a table with about 60 entries that translates the requirements for limiting global warming to below 2-degrees into concrete numbers for cumulative emissions and emission reductions required by 2050 and 2100. This is accompanied by a detailed table showing the costs for these future pathways.
The IPCC represents the costs as consumption losses as compared to a hypothetical 'business-as-usual' case. The table does not only show the median of all scenarios, but also the spread among the models. It turns out that the costs appear to be moderate in the medium-term until 2030 and 2050, but in the long-term towards 2100, a large spread occurs and also high costs of up to 11% consumption losses in 2100 could be faced under specific circumstances. However, translated into reduction of growth rate, these numbers are actually quite low. Ambitious climate protection would cost only 0.06 percentage points of growth each year. This means that instead of a growth rate of about 2% per year, we would see a growth rate of 1.94% per year. Thus economic growth would merely continue at a slightly slower pace. However, and this is also said in the report, the distributional effects of climate policy between different countries can be very large. There will be countries that would have to bear much higher costs because they cannot use or sell any more of their coal and oil resources or have only limited potential to switch to renewable energy.
The technological challenge
Furthermore – and this is new and important compared to the last report of 2007 – the costs are not only shown for the case when all technologies are available, but also how the costs increase if, for example, we would dispense with nuclear power worldwide or if solar and wind energy remain more expensive than expected.
The results show that economically and technically it would still be possible to remain below the level of 2-degrees temperature increase, but it will require rapid and global action and some technologies would be key:
Many models could not achieve atmospheric concentration levels of about 450 ppm CO2eq by 2100, if additional mitigation is considerably delayed or under limited availability of key technologies, such as bioenergy, CCS, and their combination (BECCS).
Probably not everyone likes to hear that CCS is a very important technology for keeping to the 2-degree limit and the report itself cautions that CCS and BECCS are not yet available at a large scale and also involve some risks. But it is important to emphasize that the technological challenges are similar for less ambitious temperature limits.
The institutional challenge
Of course, climate change is not just a technological issue but is described in the report as a major institutional challenge:
Substantial reductions in emissions would require large changes in investment patterns
Over the next two decades, these investment patterns would have to change towards low-carbon technologies and higher energy efficiency improvements (see Figure 1). In addition, there is a need for dedicated policies to reduce emissions, such as the establishment of emissions trading systems, as already existent in Europe and in a handful of other countries.
Since AR4, there has been an increased focus on policies designed to integrate multiple objectives, increase co‐benefits and reduce adverse side‐effects.
The growing number of national and sub-national policies, such as at the level of cities, means that in 2012, 67% of global GHG emissions were subject to national legislation or strategies compared to only 45% in 2007. Nevertheless, and that is clearly stated in the SPM, there is no trend reversal of emissions within sight – instead a global increase of emissions is observed.Trends in emissions
A particularly interesting analysis, showing from which countries these emissions originate, was removed from the SPM due to the intervention of some governments, as it shows a regional breakdown of emissions that was not in the interest of every country (see media coverage here or here). These figures are still available in the underlying chapters and the Technical Summary (TS), as the government representatives may not intervene here and science can speak freely and unvarnished. One of these figures shows very clearly that in the last 10 years emissions in countries of upper middle income – including, for example, China and Brazil – have increased while emissions in high-income countries – including Germany – stagnate, see Figure 2. As income is the main driver of emissions in addition to the population growth, the regional emissions growth can only be understood by taking into account the development of the income of countries.
Historically, before 1970, emissions have mainly been emitted by industrialized countries. But with the regional shift of economic growth now emissions have shifted to countries with upper middle income, see Figure 2, while the industrialized countries have stabilized at a high level. The condensed message of Figure 2 does not look promising: all countries seem to follow the path of the industrialized countries, with no "leap-frogging" of fossil-based development directly to a world of renewables and energy efficiency being observed so far.
But the fact that today's emissions especially rise in countries like China is only one side of the coin. Part of the growth in CO2 emissions in the low and middle income countries is due to the production of consumption goods that are intended for export to the high-income countries (see Figure 3). Put in plain language: part of the growth of Chinese emissions is due to the fact that the smartphones used in Europe or the US are produced in China.
The philosophy of climate change
Besides all the technological details there has been a further innovation in this report, that is the chapter on "Social, economic and ethical concepts and methods". This chapter could be called the philosophy of climate change. It emphasizes that
Issues of equity, justice, and fairness arise with respect to mitigation and adaptation. […] Many areas of climate policy‐making involve value judgements and ethical considerations.
This implies that many of these issues cannot be answered solely by science, such as the question of a temperature level that avoids dangerous anthropogenic interference with the climate system or which technologies are being perceived as risky. It means that science can provide information about costs, risks and co-benefits of climate change but in the end it remains a social learning process and debate to find the pathway society wants to take.
The report contains many more details about renewable energies, sectoral strategies such as in the electricity and transport sector, and co-benefits of avoided climate change, such as improvements of air quality. The aim of Working Group III of the IPCC was, and the Co-Chair emphasized this several times, that scientists are mapmakers that will help policymakers to navigate through this difficult terrain in this highly political issue of climate change. And this without being policy prescriptive about which pathway should be taken or which is the "correct" one. This requirement has been fulfilled and the map is now available. It remains to be seen where the policymakers are heading in the future.
The report :
Climate Change 2014: Mitigation of Climate Change – IPCC Working Group III Contribution to AR5
Brigitte Knopf is head of the research group Energy Strategies Europe and Germany at the Potsdam Institute for Climate Impact Research (PIK) and one of the authors of the report of the IPCC Working Group III and is on Twitter as @BrigitteKnopf
Sunday, March 30, 2014
IPCC report finds world might be irreversibly changed
The report also assesses research into the projected future impact of climate change. Findings are that: