Dr. James Hansen, preeminent climate researcher, told the world today that scientists have grossly underestimated the severity of the effects of carbon dioxide emissions.
The European Union (EU) has set the boldest CO2 reduction plans in the world with a target cap of 550 parts per million (ppm) CO2. Today, James Hansen of NASA told the EU that much deeper cuts to 350 ppm CO2 would be required to stabilize the climate at near present conditions.Hansen based the target of 350 ppm on recent paleoclimate research which has showed that earth's climate is much more sensitive to CO2 increases than was previously recognized.
"If you leave us at 450ppm for long enough it will probably melt all the ice - that's a sea rise of 75 metres. What we have found is that the target we have all been aiming for is a disaster - a guaranteed disaster," Hansen told the Guardian.
Dr. Hansen has extensively studied the earth's climate record since the end of the age of the dinosaurs. Natural climate variations over the last half million years show the sensitivity of climate to carbon dioxide (CO2)in detail.
By Source: James Hansen et. al.
He has found that the earth is about twice as sensitive to a doubling of carbon dioxide levels as was previously estimated. Pollution by aerosols has obscured some of the effect of increased CO2. Lags in response have obscured the rest of the warming. Warming will continue for many years after CO2 emissions are stopped because of effects "already in the pipeline".
Carbon dioxide levels need to reduced from the present level of about 385ppm to 350ppm to stabilize global climate to preserve the conditions of the planet that have supported human civilization.
By source: James Hansen et. al.
About 4 degrees Fareinheit of additional warming is due to take place from emissions that have been already released (links to PDF).
Warming "in the pipeline". The expanded time scale for the industrial era (Fig. 2) reveals a growing gap between actual global temperature (purple curve) and equilibrium (long-term)temperature response based on the net estimated forcing (black curve). Ocean and ice sheet response times together account for this gap, which is now 2.0°C.
The forcing in Fig. 2 (black curve, Fe scale), when used to drive a global climate model (5), yields global temperature change that agrees closely (fig. 3 in 5) with observations (purple curve, Fig. 2). That climate model, which includes only fast feedbacks, has additional warming of ~0.6°C in the pipeline today because of ocean thermal inertia (5, 8).
The remaining gap between equilibrium temperature for current atmospheric composition and actual global temperature is ~1.4°C. This further 1.4°C warming to come is due to the slow surface albedo feedback, specifically ice sheet disintegration and vegetation change.
However, CO2 emissions are increasing rapidly. The recent rate of CO2 emissions increase is triple the rate of increase of the decade of 1991-2000. Industrialization of China, cutting and burning of rain forests, and major droughts have all contributed to the rapid increase of CO2 emissions.
By source: NOAA
We are rapidly approaching CO2 levels that, if maintained, will cause all the planet's ice to melt. Moreover, there are feedbacks such as the oxidation of arctic peat and the melting and outgassing of methane hydrate ices that are already adding to atmospheric CO2.
A drastic change in energy policy is necessary to avert catastrophe. CO2 emissions from coal plants must be terminated or CO2 levels will continue to increase. Electric powered transportation will be necessary. Deforestation must cease.
The meltdown we saw this summer is the beginning of a meltdown of civilization if we don't stop releasing greenhouse gases to the atmosphere.