Not a pretty picture: recent science summarised

By Bryan Walker 17/10/2011

A valuable review, Climate Science 2009-2010, has just been published by the World Resources Institute. It’s a summary of major peer-reviewed research in climate change science and technology during those two years. Aimed at policymakers, the NGO community, and the media, it offers succinct summaries of the findings of a wide array of scientific papers, a short discussion of the implications of each paper, and brief overviews along the way of where the research is pointing.

It’s 48 pages in length, not a quick read but tailored for easy comprehension for anyone with a general lay understanding of climate science.  A sample list of some of the findings is provided at the start, but the full survey is well worth reading through. The range of papers is a reminder of how much scientific work is being done and how the full picture is built from many studies and a great variety of detailed investigations. The review is restrained in its drawing of implications from the studies, often pointing to the need for further investigation and certainly not hyping any of the results. Nevertheless it’s apparent that the recent research continues to reveal grim prospects for humanity as emissions continue to rise.

The papers surveyed are grouped into four sections.

Physical climate: In this section the stand-out areas are climate feedbacks and sea level rise. Global temperature is clearly continuing to increase and the climate science literature of 2009 and 2010 has advanced the understanding of climate feedbacks. The review discusses a study of ocean methane hydrates as a slow tipping point in the global carbon cycle, noting the implication that if the Earth warms by 3°C, which is not beyond the scope of possibility during the next century, this feedback could add 17 percent to projected global average temperature increases.  A couple of papers look at the possible effect of climate change on ozone depletion and vice versa. Aerosol effects are examined in two papers: one allows weight to the absorptive effect of black carbon and suggests that the cooling effect of anthropogenic aerosols is less powerful than previously assumed; the other finds that the comparatively accelerated warming of the tropical North Atlantic in the past three decades is partly due to a reduction in cooling dust particles from the Sahara, itself a phenomenon which may be linked to climate change-induced changes in moisture and winds. Andrew Dessler’s important 2010 paper on cloud feedback is described as providing new evidence suggesting that the sign of the cloud feedback is moderately positive. Further papers examine feedbacks from soils, peatlands and the diminution of Arctic ice cover. The effect of the latter is already under way.

There has been considerable change in predictions of sea level rise since the last IPCC report in 2007. They are all higher than the 0.18 to 0.59 metres by 2100 nominated by the IPCC (albeit with the caveat that it could be more depending on the behaviour of polar ice sheets).  The review mentions several studies and focuses especially on two in 2010 which estimated a range between 0.59 and 1.8 metres by 2100. Another study in 2009 approached the question from the standpoint of glacier equilibrium and found that on average glaciers are 23 percent below equilibrium — that is, the area accumulating new snow is far less than that sufficient to maintain the current glacier size even without further global warming. The conclusion was that we are already committed to 1.8 meters of sea level rise resulting from ice loss, and that 3.7 meters is possible over the next century if we continue to warm without climate mitigation activities.  The vulnerability of parts of the US coastline to the uneven effects of sea level rise is addressed in other studies.

In the interests of brevity I’ll list some of the samples provided for the other three sections.

Hydrological Cycle:

  • Observations show that multi-year (MY) winter sea ice area decreased by 42 percent between 2005 and 2008 and that there was a thinning of ~0.6 m in MY ice thickness over the same 4 years (average thickness of the seasonal ice in midwinter is ~2 m)
  • As much as 12 percent of the volume of Swiss alpine glaciers was lost over the period from 1999 to 2008.
  • The rate of mass loss in the East Antarctic Ice Sheet may be greater than previously estimated.
  • Changing ice dynamics in the Arctic may be leading to an increase in observed ’winter weather’ including more snow and colder temperatures in temperate regions of the Northern Hemisphere.

Ecosystems and Ecosystem Services:

  • Ocean acidification, which only recently was recognized a threat to coral in areas such as the Great Barrier Reef (and is happening much more quickly than anticipated), is now recognized as having implications for the entire ocean food web which is critical to whales, fish, and molluscs.
  • Based on human physiological estimates, a global average temperature increase of 7° C, which is toward the extreme upper part of the range of current projections, would make large portions of the world uninhabitable.
  • The impacts of projected climate change on emperor penguin populations are likely to be significant; with a 36 percent probability of ’quasi extinction’ (greater than 95 percent decline) by 2100.
  • A 28 cm future sea level rise is projected to reduce the current Bengal tiger habitat in the Sundarban region of Bangladesh by 96 percent and would likely reduce tiger numbers to 20 breeding pairs.

Climate Change Mitigation Technologies and Geoengineering:

  • Land-use change associated with planting biofuel crops can have implications on the regional average temperatures through an albedo effect.
  • Advances in more flexible, cheaper small-scale solar photovoltaics could make it easier and less expensive to integrate solar-powered electricity generation into building materials.
  • If all urban surfaces worldwide were made reflective, the heat trapping effects of urban surfaces would be eliminated, an impact greater than eliminating the annual anthropogenic emissions of the entire globe.
  • Geoengineering is being more widely studied in terms of its potential to limit global warming if efforts to reduce emissions fail, as well as its implications. The review summarizes various proposals and preliminary findings in two categories — carbon dioxide removal and solar radiation management.

When I’d finished reading the review I thought about the patient careful scientific work that it represented. The review doesn’t report any single research paper as authoritative, but there’s no denying that the credibility of climate science as a whole is only confirmed as the body of work increases.  In the political arena the strength and clarity of the science may be shouted down by blustering denial or muted by electoral timorousness, but it’s there, it’s real, and what it points to is unavoidable.

I hope a review such as this receives the attention of the policy makers for whom it is written and that our political leaders are fully aware of the science they are or are not engaging with. The media, too, owe us a proper acquaintance with the science which the review demonstrates is well within the intellectual reach of any intelligent journalist given sufficient time to absorb it.