Global warming/Temp

Graft has proposed rewriting the global warming entry, which at present is something of a mish-mash. I'm making a start by doing a mini-survey of the official status of global climate change according to as many different government websites as I can find to visit. (Anyone wants to jump in and help with this, go right ahead!) Obviously, this stuff won't make it into the final article, but I'll park it here for the time being, and it can eventually be archived off to serve as a reference to underpin the bona fides of the new entry (after it's written).

New Zealand http://www.climatechange.govt.nz/profile/profile.htm#cc

Climate change will have both environmental and economic impacts worldwide, including in New Zealand.

Scientific experts worldwide have agreed that the earth's climate is changing, probably in response to human activities. They are concerned about the impact global warming will have on our planet and our way of life in years to come. It is thought that the emission of greenhouse gases such as carbon dioxide, methane and nitrous oxide are a major cause of the earth's temperature increase.

Australia http://www.greenhouse.gov.au/ago/index

The Australian Greenhouse Office (AGO) is the world's first government agency dedicated to cutting greenhouse gas emissions. It was established in 1998 as a separate agency within the environment portfolio to provide a whole of government approach to greenhouse matters.

Climate change is an issue of major significance for all of us. Most of the world’s leading scientists agree that global warming caused by human activity is occurring. New and stronger evidence that humans are having an influence on the global climate through greenhouse gas emissions is presented in a report prepared by the Intergovernmental Panel on Climate Change in 2001.

United Kingdom http://www.defra.gov.uk/environment/climatechange/01.htm

The scientific evidence is growing that man-made greenhouse gas emissions are having a noticeable effect on the earth's climate. Globally, seven of the ten warmest years on record were in the 1990s. Current climate models predict that global temperatures could warm from between 1.4 to 5.8oC over the next 100 years, depending on the amounts of greenhouse gases emitted and the sensitivity of the climate system. The social, environmental and economic costs associated with this could be huge.

Canada http://www.ec.gc.ca/climate/home-e

Climate change has been called the most significant environmental problem the world has ever faced. For this reason the Government of Canada, Canadians and the global community are working together to share information and ideas to meet this challenge.

South Africa http://www.environment.gov.za/soer/nsoer/issues/climate/index.htm

The direct causes of atmospheric change and the enhanced greenhouse effect, are human activities such as the burning of fossil fuels and the clearing of natural vegetation for agricultural purposes.

Concentrations of carbon dioxide as measured at Cape Point show an overall increase of approximately 0.6% per year. This is a global phenomenon which is the subject of much concern and research.

Warmer temperatures in South Africa may lead to: changes in biogeographic distributions and loss of biodiversity, more human deaths, especially among the elderly, due directly to heat waves, greater risk of epidemic infectious illnesses, such as malaria (due to an expansion of suitable habitat for mosquitoes which transmit malaria).

---

Aargh. I had written three pages and mozilla crashed. Don't have the patience to do it all again. The Short, Short version. (Do you? yes. Do you? yes.)

The IPCC reports (http://www.ipcc.ch/pub/reports.htm) are something we should all read.

"The Intergovernmental Program on Climate Change (1), the World Climate Research Program CLIVAR (2), and the U.S. National Research Council (3) have identified the role of the ocean as being critical to understanding the variability of Earth's climate system." -- Levitus et al, Science 287/5461

I.e., more discussion and explanation of the role of the oceans as a heat sink is needed, as well as deep-ocean heat cycling.

Is warming happening?

Warming is claimed to have occurred in two phases in the past century, from 1925 to 1944, and from 1976 to present.

To show warming, you must show (a) there is a significant increase in temperature in the past years, (b) it is not an error in instrumentation, and (c) it deviates significantly from the historical record.

(a) is primarily obtained through surface measurements, ocean temperature measurements, and so on (this is discussed a bit in current version).

(b) The "urban heat island effect" needs discussion, as well as the important discrepancies between satellite data and surface data, and possible resolutions. As well there are claims (like by Fred Singer) that the IPCC data for post-WWII warming is based on shoddy data from remote outposts.

(c) The historical record comes from ice core samples, tree rings, and corals, and has been measured according to several models for the past thousand years.

A letter from Raymond S. Bradley responding to Fred Singer:

The evidence for warming over the last 60 years is unequivocal, even if the direct instrumental record is ignored. The change in temperature has led to a major reduction in the mass of alpine glaciers in almost all parts of the world (1), an increase in permafrost thawing at high latitudes (2) and at high altitudes (3), a reduction in the extent and thickness of Arctic sea-ice (4), later freeze-up and earlier break-up dates of ice on rivers and lakes (5), and an increase in the calving rate of Antarctic ice shelves (6). There is no evidence or reason to think that these systems have a lag response to warming of 50 years or more [e.g., (7)]. There have also been shifts in the distribution of plant and animal species, both latitudinally and altitudinally (8), changes in the phenology of plant leafing and flowering (9), and the storage of significant quantities of heat in the near-surface ocean (10), as well as an overall rise in sea-level driven by both continental ice melting and a steric change due to the increase in overall ocean temperature (11). In addition, there have been remarkable increases in ground temperatures over the last millennium (12).

Thus, regardless of arguments over instrumental versus satellite-based estimates of warming in recent decades (13), there are multiple indicators of warming in the 20th century that paint a vivid picture of the global-scale environmental consequences of the temperature increase.

(sources below if you want to read them)

Is warming caused by humans?

"Despite considerable progress, the question of whether the observed gradual increase in global mean temperature over the last century is indeed caused by human activities or is simply an expression of natural climate variability on larger spatial and temporal scales remains a controversial issue." -- K. Hasselman, Science

Warming, goes the claim, is caused by humans due to deforestation, and production of greenhouse gases, primarily carbon dioxide from burning fossil fuels, but also methane and other gases.

This is based mostly on computer models, which have several significant weaknesses.

Two kinds of models:

• General circulation models (GCM) - models of atmospheric behavior that are based mostly on modeling motion of the air, accounting for momentum, water vapor, heat, radiation. They generally have a resolution of several hundred miles and so can only model large-scale phenomenon and factors.
• Energy balance models - these model the change in temperature based on radiative equilibrium, i.e., the difference between energy coming in (from the sun) and energy going out (radiated to space). These are old and simple models, and work by dividing the earth into "zones" based on latitude, and accounting for factors such as reflectivity (albedo) of the zone, as well as transfer of energy between zones.

In addition, the early twentieth-century warming period may not be due to (mostly) human activity, since greenhouse gas forcing increased sharply after this period.

Other proposed sources are solar activity (which correlates well with earth temperature) and a decrease in volcanic activity in recent years.

Other disputes

The IPCC report in 1988 gave three possibilities for the continuation of the warming due to carbon dioxide. (i) warming continues at a linear rate. (ii) warming continues, but slows and stops due to compensatory effects (e.g., increasing absorbance by plant growth stimulated by more CO₂, or higher reflectivity resulting from greater cloud cover produced by more water evaporation). (iii) warming continues and accelerates due to additive effects, e.g. release of trapped methane in arctic ice.

Both (ii) and (iii) have evidence for them. For example, the amount of carbon in the atmosphere has not been increasing as predicted. Or, alternatively, CO₂ is not the limiting factor in most plant growth.

Sources on "Is warming happening":

1. M. B. Dyurgerov, M. F. Meier, Proc. Natl. Acad. Sci. U.S.A. 97, 1406 (2000); L. G. Thompson et al., Glob. Planet. Change 7, 145 (1993); H. H. Brecher, L. G. Thompson, Photogramm. Eng. Remote Sens. 59, 1017 (1993).
2. T. E. Osterkamp, V. E. Romanovsky, Permafrost Periglacial Proc. 10, 17 (1999).
3. H. Jin et al., Glob. Planet. Change 26, 387 (2000).
4. D. A. Rothrock et al., Geophys. Res. Lett. 26, 3469 (1999); P. Wadhams, N. R. Davis, Geophys. Res. Lett. 27, 3973 (2001); K. Vinnikov et al., Science 286, 1934 (1999).
5. J. J. Magnuson et al., Science 289, 1743 (2000).
6. T. A. Scambos et al., Ann. Glaciol. 46, 516 (2000).
7. G. Patzelt, M. Aellen, Mitt. Naturforsch. Versuchsanst. Wasserbau Hydrol. Glazioloogie ETH Zurich 108, 49 (1990).
8. G. Grabherr et al., Nature 369, 448 (1994); H. Pauli et al., World Resources Rev. 8, 382 (1996).
9. R. B. Myneni et al., Nature 386, 698 (1997).
10. S. Levitus et al., Science 287, 2225 (2000).
11. R. Warrick, J. Oerlemans, in Climate Change: The IPCC Scientific Assessment, J. T. Houghton et al., Eds. (Cambridge Univ. Press, Cambridge, 1990).
12. S. Huang et al., Nature 403, 756 (2000); R. N. Harris, D. S. Chapman, Geophys. Res. Lett. 28, 747 (2001).
13. National Research Council, Reconciling Observations of Global Temperature Change (National Academy Press, Washington, DC, 2000).