The Scientific Imperatives Project
Serious global warming impacts are happening both more rapidly and at lower global temperature increases than projected. Observations suggest the planet has passed, or is close to passing, significant climate tipping points. The growing impact of carbon cycle feedbacks and further temperature increases due to thermal inertia (lags in the system), suggest that the current level of greenhouse gases is greater than that which would enable the maintenance of the planet’s biodiversity and ecosystems and food production and secure water supplies for all people, a condition termed a safe climate.
The complete loss of Arctic sea-ice in summer would likely create conditions for significant ice-mass loss from Greenland and, combined with further temperature increases in the system and Arctic amplification, produce an unacceptable risk that significant amounts of permafrost and Arctic Ocean carbon would be mobilised.
Eminent climate researchers such as James Hansen of NASA and Hans Joachim Schellnhuber of the Potsdam Institute suggest that greenhouse gas levels in the range 280-325ppm CO2 are likely to be consistent with a safe climate, the achievement of which would require zero or near-zero anthropogenic greenhouse gas emissions and the sequestration of a significant amount of existing atmospheric carbon.
The purpose of the Safe Climate Australia climate science imperatives project is to review literature, identify knowledge gaps and undertake/commission and synthesise research to ascertain:
- what are the range of safe-climate conditions that allow the maintenance of the world’s bio-diverse ecosystems, and the capacity to secure adequate food and water for the human population
- what emissions reduction trajectory and drawing down of existing atmospheric carbon would be consistent with achieving that aim, and
- what other actions may be necessary to achieve these aims.
In particular the project will seek to answer the following questions:
- What is the optimal range of conditions of the global climate system needed to maintain the planet’s biodiversity and ecosystems and for the maintenance of food production and secure water supplies for all people?
- What is the optimal range of global climate system conditions needed to prevent the loss of significant permafrost/Arctic Ocean carbon stores; and prevent the loss of and/or re-establish the conditions for the maintenance of year-round Arctic sea-ice, and the Himalayan, Greenland and Antarctic ice sheets?
- Are there any other considerations that would lead to the need to stabilise the carbon dioxide level of the atmosphere at a lower level than that needed to re-establish a resilient and adequately extensive Arctic sea-ice cover?
- What is the precautionary level or range of greenhouse gases, and what level of drawdown of atmospheric carbon would be required, consistent with achieving the conditions described in 1 and 2?
- What speed of action is required to establish the conditions described in 1 and 2, such that significant tipping points which would preclude the attainment of this objective are not passed? In particular, what is the time frame for establishing sufficient cooling at the poles to avoid the mobilisation of permafrost carbon stores and prevent significant sea level rise caused by the substantial loss of polar ice sheets?
- If the establishment of the range of conditions specified in 5 requires emissions of greenhouse gases to be reduced rapidly to zero or near zero, what additional actions may be required if the consequent loss of cooling aerosols would produce an unsafe level or speed of warming?
- What are the most promising techniques and programmes for rapidly reducing greenhouse gas emissions and for rapidly drawing down excess atmospheric carbon and sequestering it?
- If it is established that it is necessary for greenhouse gas emissions to be reduced to zero or near zero, and efforts to achieve this goal and to draw excess carbon dioxide out of the air cannot, by themselves, maintain the planet’s biodiversity and ecosystems and food production and secure water supplies for all people, what methods and technologies should be considered to directly cool the planet?