Cumulative carbon emissions, emissions floors and short-term rates of warming: implications for policy

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 369. N° 1934. Bowerman Niel H.A.; Frame David J.; Huntingford Chris; et al. - The Royal Society, 2011

A number of recent studies have found a strong link between peak human-induced global warming and cumulative carbon emissions from the start of the industrial revolution, while the link to emissions over shorter periods or in the years 2020 or 2050 is generally weaker. However, cumulative targets appear to conflict with the concept of a ‘floor’ in emissions caused by sectors such as food production. Here, we show that the introduction of emissions floors does not reduce the importance of cumulative emissions, but may make some warming targets unachievable. For pathways that give a most likely ...

English

[article] 

Cumulative carbon emissions, emissions floors and short-term rates of warming: implications for policy

Niel H.A. Bowerman ; David J. Frame ; Chris Huntingford ; Jason A. Lowe ; Myles R. Allen

in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences > Vol. 369. N° 1934 (2011) . - p. 45-66

A number of recent studies have found a strong link between peak human-induced global warming and cumulative carbon emissions from the start of the industrial revolution, while the link to emissions over shorter periods or in the years 2020 or 2050 is generally weaker. However, cumulative targets appear to conflict with the concept of a ‘floor’ in emissions caused by sectors such as food production. Here, we show that the introduction of emissions floors does not reduce the importance of cumulative emissions, but may make some warming targets unachievable. For pathways that give a most likely warming up to about 4°C, cumulative emissions from pre-industrial times to year 2200 correlate strongly with most likely resultant peak warming regardless of the shape of emissions floors used, providing a more natural long-term policy horizon than 2050 or 2100. The maximum rate of CO2-induced warming, which will affect the feasibility and cost of adapting to climate change, is not determined by cumulative emissions but is tightly aligned with peak rates of emissions. Hence, cumulative carbon emissions to 2200 and peak emission rates could provide a clear and simple framework for CO2 mitigation policy.

Language(s): English

Format: Digital (Free)

Tags: Climate change ; Climate ; Greenhouse gas (GHG) ; Politics ; Greenhouse gas reducing ; Scenario Add tag

[article] 

No review, please log in to add yours !

Sea-level rise and its possible impacts given a ‘beyond 4°C world’ in the twenty-first century

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 369. N° 1934. Nicholls Robert J.; Marinova Natasha; Lowe Jason A.; et al. - The Royal Society, 2011

The range of future climate-induced sea-level rise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-level rise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m—the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the i ...

English

[article] 

Sea-level rise and its possible impacts given a ‘beyond 4°C world’ in the twenty-first century

Robert J. Nicholls ; Natasha Marinova ; Jason A. Lowe ; Sally Brown ; Pier Vellinga ; Diogo de Gusmão ; Jochen Hinkel ; Richard S.J. Tol

in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences > Vol. 369. N° 1934 (2011) . - p. 161-181

The range of future climate-induced sea-level rise remains highly uncertain with continued concern that large increases in the twenty-first century cannot be ruled out. The biggest source of uncertainty is the response of the large ice sheets of Greenland and west Antarctica. Based on our analysis, a pragmatic estimate of sea-level rise by 2100, for a temperature rise of 4°C or more over the same time frame, is between 0.5 m and 2 m—the probability of rises at the high end is judged to be very low, but of unquantifiable probability. However, if realized, an indicative analysis shows that the impact potential is severe, with the real risk of the forced displacement of up to 187 million people over the century (up to 2.4% of global population). This is potentially avoidable by widespread upgrade of protection, albeit rather costly with up to 0.02 per cent of global domestic product needed, and much higher in certain nations. The likelihood of protection being successfully implemented varies between regions, and is lowest in small islands, Africa and parts of Asia, and hence these regions are the most likely to see coastal abandonment. To respond to these challenges, a multi-track approach is required, which would also be appropriate if a temperature rise of less than 4°C was expected. Firstly, we should monitor sea level to detect any significant accelerations in the rate of rise in a timely manner. Secondly, we need to improve our understanding of the climate-induced processes that could contribute to rapid sea-level rise, especially the role of the two major ice sheets, to produce better models that quantify the likely future rise more precisely. Finally, responses need to be carefully considered via a combination of climate mitigation to reduce the rise and adaptation for the residual rise in sea level. In particular, long-term strategic adaptation plans for the full range of possible sea-level rise (and other change) need to be widely developed.

Language(s): English

Format: Digital (Free)

Tags: Sea level rising ; Climate change ; Climate ; Melting Ice ; Global warming ; Scenario Add tag

[article] 

No review, please log in to add yours !

When could global warming reach 4°C?

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 369. N° 1934. Betts Richard A.; Collins Matthew; Hemming Deborah L.; et al. - The Royal Society, 2011

The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) assessed a range of scenarios of future greenhouse-gas emissions without policies to specifically reduce emissions, and concluded that these would lead to an increase in global mean temperatures of between 1.6°C and 6.9°C by the end of the twenty-first century, relative to pre-industrial. While much political attention is focused on the potential for global warming of 2°C relative to pre-industrial, the AR4 projections clearly suggest that much greater levels of warming are possible by the end of the twenty-fir ...

English

[article] 

When could global warming reach 4°C?

Richard A. Betts ; Matthew Collins ; Deborah L. Hemming ; Chris D. Jones ; Jason A. Lowe ; Michael G. Sanderson

in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences > Vol. 369. N° 1934 (2011) . - p. 67 -84

The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) assessed a range of scenarios of future greenhouse-gas emissions without policies to specifically reduce emissions, and concluded that these would lead to an increase in global mean temperatures of between 1.6°C and 6.9°C by the end of the twenty-first century, relative to pre-industrial. While much political attention is focused on the potential for global warming of 2°C relative to pre-industrial, the AR4 projections clearly suggest that much greater levels of warming are possible by the end of the twenty-first century in the absence of mitigation. The centre of the range of AR4-projected global warming was approximately 4°C. The higher end of the projected warming was associated with the higher emissions scenarios and models, which included stronger carbon-cycle feedbacks. The highest emissions scenario considered in the AR4 (scenario A1FI) was not examined with complex general circulation models (GCMs) in the AR4, and similarly the uncertainties in climate–carbon-cycle feedbacks were not included in the main set of GCMs. Consequently, the projections of warming for A1FI and/or with different strengths of carbon-cycle feedbacks are often not included in a wider discussion of the AR4 conclusions. While it is still too early to say whether any particular scenario is being tracked by current emissions, A1FI is considered to be as plausible as other non-mitigation scenarios and cannot be ruled out. (A1FI is a part of the A1 family of scenarios, with ‘FI’ standing for ‘fossil intensive’. This is sometimes erroneously written as A1F1, with number 1 instead of letter I.) This paper presents simulations of climate change with an ensemble of GCMs driven by the A1FI scenario, and also assesses the implications of carbon-cycle feedbacks for the climate-change projections. Using these GCM projections along with simple climate-model projections, including uncertainties in carbon-cycle feedbacks, and also comparing against other model projections from the IPCC, our best estimate is that the A1FI emissions scenario would lead to a warming of 4°C relative to pre-industrial during the 2070s. If carbon-cycle feedbacks are stronger, which appears less likely but still credible, then 4°C warming could be reached by the early 2060s in projections that are consistent with the IPCC’s ‘likely range’.

Language(s): English

Format: Digital (Free)

Tags: Climate change ; Climate ; Global warming ; Scenario Add tag

[article] 

No review, please log in to add yours !