Why do we care about dangerous climate change?

Why do we care about dangerous climate change?

Over the next 40 years or so we are unfortunately going to see human induced climate change regardless of human attempts to prevent it (Wigley et al., 2005). Inertia within the climate system (primarily caused by the oceans absorbing massive amounts of energy and gradually releasing it into the climate system), means that the impact of emissions in the present will still be taking effect in decades to come. This is what people are talking about when they say change in the pipeline or Climate Change Commitment.

This figure from Murphy et al., 2009 shows just how substantial the ccean heat uptake has been over the past 50 years relative to the land and atmosphere  

The key point is that when we talk about stabilising GHG concentrations, the ultimate goal is not to instantaneously stop climate change in its tracks, but to constrain it within 'manageable levels' (Taken from the Energy and Climate Change Committee's 2014 report)

Climate change happens naturally on a variety of timescales ranging from decades, to millions of years. There is great deal of research on the role of past climate variability on human societies, and biodiversity (I’ve put a list of some interesting links at the bottom). The world that we see around us is in many respects a testament of resilience to this change. However, in the context of anthropogenic climate change, where GHG concentrations and associated radiative forcing are with a ‘very high confidence’ occurring at rates unprecedented in the past 22,000 years and most probably the last 800,000 years (although confidence in this statement is restricted by a present lack of high resolution records going back to that date), this resilience is likely to be put under extreme stress.

This is where the concept of dangerous climate change comes in.

As Stephen H. Schneider and Janica Lane comment, danger has become a buzzword used so often in the climate change context that it has become cliché and suffers from a lack of conceptual clarity. Despite this fact, the term dangerous climate change was initially formulated at the 1992 United Nations Framework Convention on Climate Change (UNFCCC) with a strict meaning and purpose.

Dangerous climate change was defined as change which:

§  Does not allow ecosystems to adapt naturally;

§  Threatens food production;

§  Does not enable economic development to proceed in a sustainable manner (UN, 1992)

The term was to be used as a baseline to guide mitigate efforts, one designed to simply present the threat at hand. While no formal attempt was made by the UNFCCC in 1992 to quantify a level of climate change considered dangerous, the term has since become heavily linked to a 2^oC global warming limit relative to pre-industrial temperatures (Randalls, 2010).

“2^oC of global warming to allow ecosystems to adapt naturally, food production to continue un-threatened and economic development to continue in a sustainable manner, what a conveniently precise and rounded figure” I hear you say. Well you guessed right, I (and a large portion of the scientific community I might add) am not convinced.

So get ready for my next post where I explain exactly where this number comes from and why it is so difficult to quantify dangerous climate change.

Here is my Secret Link and some interesting papers on the links between past climate change, evolution and societal development: 

Maslin M.A., C. Brierley, A. Milner, S. Shultz, M. Trauth, K. Wilson “East African climate pulses and early human evolution” Quaternary Science Reviews (2014) 

Willis, K. J., Bennett, K. D., Bhagwat, S. A., & Birks, H. J. B. (2010). 4° C and beyond: what did this mean for biodiversity in the past?. Systematics and Biodiversity, 8(1), 3-9.