Later On

A blog written for those whose interests more or less match mine.

The physical realities of global warming

with 2 comments

Basically, all the latest measurements show that we’re doing worse than the most pessimistic projections. This latest post at Skeptical Science is well worth reading—and ponder the graphs. The post begins:

Global warming is happening before our very eyes. All over the world, from the Arctic to Antarctica, scientists are observing the impacts of climate change. In the three years since the IPCC Fourth Assessment Report (AR4) was drafted, hundreds of peer reviewed papers studying climate change have been published. A summary of the latest research has been compiled in The Copenhagen Diagnosis, released by the University of NSW and authored by 26 climate scientists. It’s a resource heavy report, referencing hundreds of papers. Here are some of the highlights:

At a time when we need to be lowering our carbon footprint, global CO2 emissions have been sharply rising. In fact, the acceleration in fossil fuel CO2 emissions is tracking the worst case scenarios used by the IPCC AR4. Consequently, atmospheric CO2 is increasing ten times faster than any rate detected in ice core data over the last 22,000 years.

CO2_Emissions_Model_Obs
Figure 1: Observed global CO2 emissions from fossil fuel burning and cement production compared with IPCC emissions scenarios. The coloured area covers all scenarios used to project climate change by the IPCC.

Over the past 25 years, global temperature has warmed at a rate of ~0.2°C per decade. Superimposed over this long term trend is short term variability. Most of these short-term variations are due to internal oscillations like El Niño Southern Oscillation, the 11-year solar cycle and volcanic eruptions. Over periods less than a decade, such short-term variations can outweigh the anthropogenic global warming trend. For example, El Niño events can change global temperature by up to 0.2°C over a few years. The solar cycle imposes warming or cooling of 0.1°C over five years. However, neither El Niño, solar activity or volcanic eruptions make a significant contribution to long-term climate trends. Consequently, over the past decade (1999-2008), the warming trend is 0.19°C per decade. consistent with the long term trend.

Global_Temp_Change
Figure 2: Global temperature according to NASA GISS data since 1980. The red line shows annual data, the red square shows the preliminary value for 2009, based on January-August. The green line shows the 25-year linear trend (0.19 °C per decade). The blue lines show the two most recent ten-year trends (0.18 °C per decade for 1998-2007, 0.19 per decade for 1999-2008).

Satellite and tide-gauge measurements show that sea level rise is accelerating faster than expected. The average rate of rise for 1993-2008 as measured from satellite is 3.4 millimeters per year while the IPCC Third Assessment Report (TAR) projected a best estimate of 1.9 millimeters per year for the same period. Actual sea level rise is 80% faster than projected by models. Sea level is likely to rise much more by 2100 than the often-cited range of 18-59 centimeters from the IPCC AR4…

Read it all—there are more graphs. And note that sea level has risen 6 cm just since 1990. After more graphs and a list of findings, he concludes:

… There is a common theme emerging from the most recent peer-reviewed research. When uncertainties expressed in the IPCC AR4 report are subsequently resolved, they point to a more rapidly changing and more sensitive climate than previously believed. Skeptics tend to characterise the IPCC as imposing an alarmist bias in their conclusions. The latest empirical data indicates the opposite is the case.

Written by LeisureGuy

25 November 2009 at 10:55 am

2 Responses

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  1. May I use Wikipedia content in my blog without violating the copyright law? How can I do that? Explain in details please..

    Benedikta

    11 March 2012 at 4:07 am

  2. Legal questions should be addressed to lawyers. I am not a lawyer.

    LeisureGuy

    11 March 2012 at 6:58 am


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