IPCC Projections on Climate Change: Are the Models Wrong?

The Intergovernmental Panel on Climate Change (IPCC) says:
"Climate Change is mainly anthropogenic (man-made)"

For a biblical view see: It's God's Weather
For a climate sceptic view see: Solar Irradiance

Recent Sea Level Rise

Fig.2: Recent Sea Level Rise

Image courtesy Global Warming Art

Loss of Arctic Sea Ice

Fig.3: Arctic Sea Ice Loss (EPA)

Image courtesy US Environmental Protection Agency

Glacier Shortening

Fig.4: Glacier Shortening

Image courtesy B. Robinson, N. Robinson, and W. Soon Global Warming Petition Project

Climate Change Attribution

Fig.5: Climate Change Attribution

Image courtesy Robert A. Rohde
Global Warming Art

Related topics:
It's God's Weather
End Times

CO2 Variation

Fig.8: CO2 Variation

Image courtesy Robert A. Rohde
Global Warming Art

Recent Carbon Emissions

Fig.9: Recent Carbon Emissions

Image courtesy Mak Thorpe

Evidence of Global Warming

Most climate scientists agree that climate change (as in global warming) is happening, although recently global warming may have slowed or stopped. Figure 1 shows global average temperatures as compiled by the NASA's Goddard Institute for Space Studies (GISS). Data is from surface air measurements at meteorological stations and from ship and satellite sea surface temperature (SST) measurements. The zero on this figure is the mean temperature from 1961-1990.

Recent Global Temperature Rise

Fig.1: Recent Global Temperature Rise (Courtesy NASA GISS)

[This graph uses 'adjusted' temperature data, not what was reported from weather stations]

Offical statements on global warming:

"The January-November 2010 surface temperature anomalies are the warmest (along with 2005) in the 131 year analysis period. Global warming amounts to 0.8 °C over the past century, with the largest warming in remote regions including high latitudes" [ NASA GISS ]
"The UK has experienced 9 of the 10 warmest years on record since 1990" [ UK Met Office ]
"Eleven of the 12 hottest years on record have occurred since 2001" [ World Meteorological Organisation ]
"Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850" [ IPCC AR5 2013 ]

Other evidence of warming: Sea levels have risen by 17 cm worldwide since 1900 (Fig.2), Arctic sea ice has been declining since the late 1970s (Fig.3), and glaciers have been retreating since about 1850 (Fig.4). Malaria has spread to higher altitudes and at least 279 species of plants and animals are moving closer to the poles.

What does the IPCC say?

The Intergovernmental Panel on Climate Change or IPCC is a scientific intergovernmental body established by the UN and the World Meteorological Organization. Nearly 200 countries are members of the IPCC. It's main activity is to provide regular reports of the state of knowledge on climate change based on the work of thousands of scientists from all over the world. More than 800 authors are involved in writing the reports. The IPCC's fifth assessment report (AR5) of 2013 states:

"There is consistent evidence from observations of a net energy uptake of the earth system due to an imbalance in the energy budget. It is virtually certain that this is caused by human activities, primarily by the increase in CO2 concentrations. Global average temperatures could be more than 2 degrees above average by 2100, and could reach 4.8 degrees"

Climate Modelling and Prediction

Climate models are mathematical representations of the interactions between the atmosphere, oceans, land surface, ice and the sun. They assume CO2 is a major player in climate change and so predictions are now based upon various scenarios for global greenhouse gas (GHG) and aerosol concentrations. These are called Representative Concentration Pathways (RCPs).

CO2 Attribution:

The modelling in Fig.5 (Meehl et al, 2004) was claimed to represent the consensus view with respect to climate change attribution. Specifically, it suggests that the natural variations of solar and volcanic activity cannot on their own account for warming. And man-made sulfate emmissions actually reduce global temperature. It is claimed that the model is only able to simulate the temperature record over the past century when GHGs are included in the model. This suggests that GHG increase is crucial to the warming process (but many dispute this; see for example Zbigniew Jaworowski and solar irradiance changes).

Model Reliability:

It is interesting to compare model predictions of future temperature rise. The UK Met Office model HadCM3 was used in the IPCC Third Assessment Report (AR3, 2001) and model HadGEM1 used in the IPCC Fourth Assessment Report (AR4, 2007). It was claimed these models gave good simulation of current climate. Figure 6 shows some early model predictions, giving a 2-5 °C rise by 2100 (a 5°C rise is equivalent to the change in mean temperature from the last ice age to today).

Early Global Warming Projections

Fig.6: Early Global Warming Projections

Image: Robert A. Rohde Global Warming Art

IPCC AR5 Global Warming Projections

Fig.7: IPCC AR5 Global Warming Projections

Image: IPCC Summary

Figure 7 shows global warming projections from IPCC AR5, 2013. Significantly, maximum warming projections are generally reduced compared to Fig.6:

"World temperatures could rise by between 1.1 and 6.4°C during the 21st century" [ IPCC AR4, 2007 ]
"Global surface temperature change by 2100 is likely to exceed 1.5°C relative to 1850 to 1900 for all RCP scenarios except RCP2.6. It is likely to exceed 2°C for RCP6.0 and RCP8.5" [ IPCC AR5, 2013 ]

GHGs and Anthropological Warming

The major GHG concentrations are about 7600 ppm for water vapour, 390 ppm for CO2, and 1780 ppb for methane (CH4) (ppm = parts per million by volume, ppb = parts per billion by volume). Ozone and Nitrous Oxide have smaller concentraions. It is claimed that these translate to a greenhouse warming effect of 36-70% for water vapour, 9-26% for CO2, and 4-9% for CH4. Note that CH4 is about eighty times stronger as a greenhouse gas than CO2, but it is present in much smaller concentrations.

Figure 8 shows that CO2 has had a cyclic variation (period approximately 100,000 years) and the graph peaks correspond to interglacial periods. This natural climatic variation may be due in part to the 100,000 year period of the eccentricity of the earth's orbit (Milutin Milankovitch).

The significant point in Fig.8 is that each peak in the cycle levelled at approximately 278 ppm until the industrial revolution around 1850. Since then, the CO2 level has increased dramatically, reaching 400 ppm in 2013! This recent 44% increase in atmospheric CO2 appears to be a sudden departure from the natural variation, with the implication that human activity is responsible for global warming. The IPCC therefore calls this 'anthropogenic warming' (anthropogenic CO2 is that portion of CO2 in the atmosphere that is produced directly by human activities). Moreover, assuming different levels of human economic development, population growth, and fossil-fuel use, IPCC predictions for atmospheric CO2 levels lie between 500 ppm and 900 ppm by 2100!

Climate sceptics claim that fluctuation in solar irradiance is the main driving force for climate change, not CO2, but this claim is countered by the UK Met Office:
"Changes in solar activity do affect global temperatures, but research shows that, over the last 50 years, increased greenhouse gas concentrations have a much greater effect than changes in the Sun's energy".

The Consequences

According to adherents of the IPCC view, the physical consequences of warming are catastrophic: e.g. increased drought, flooding, and severe storms. Gulf Stream slow-down could plunge the USA and NW Europe into cold and drought. The social consequences are summarised in a few key reports:

  • A Pentagan Report points to possible "catastrophic droughts, famines and riots, with skirmishes over food and water, mass migration and economic disruption. Starvation and disease will decrease population size".
  • The Stern Report says "climate change will affect the basic elements of life (water, food production, health and the environment). Hundreds of millions of people could be affected by coastal flooding".

Are the IPCC Climate Models Wrong?

The IPCC position on global warming is that concentrations of certain greenhouse gases have dramatically increased due to the burning of fossil fuels and deforestation and that this probably accounts for most of the warming over the past 50 years:

"(there is) a net energy uptake of the earth system ... it is virtually certain that this is caused by human activities, primarily by the increase in CO2 concentrations." [IPCC AR5, 2013]

Certainly, carbon emissions have increased dramatically since 1950 (Fig.9). The IPCC also claims that the majority of climate scientists agree with this position and that it has been endorsed by more than 50 scientific societies and academies of science. Challenges to this theory from climate sceptics are dismissed in Skeptical Science and by offical bodies like the The Royal Society.

On the other hand, many respected climate scientists refute the IPCC claim:

"Any reasonable scientific analysis must conclude the basic theory wrong!"
[NASA Scientist Dr. Leonard Weinstein]

and tens of thousands of scientists have signed the Global Warming Project Petition. Why?