Overview of the combined effects of mitigation timing and technology availability on achievability of either not-to-exceed targets (in terms of maximum 2010–2100 temperature increase, upper panels), or 2100 temperature targets that allow for temporary overshoot (lower panels)

<p><strong>Figure 5.</strong> Overview of the combined effects of mitigation timing and technology availability on achievability of either not-to-exceed targets (in terms of maximum 2010–2100 temperature increase, upper panels), or 2100 temperature targets that allow for temporary overshoot (lower panels). Graphs show economic challenges (color shading) in terms of aggregated policy costs (left panels (a), (c)), and transitional growth reduction (right panels (b), (d)), as a function of temperature targets reached with 67% likelihood. Dark gray areas at the base of bars indicate temperature target levels that were not achieved with the range of carbon price paths assumed.</p> <p><strong>Abstract</strong></p> <p>While the international community aims to limit global warming to below 2 ° C to prevent dangerous climate change, little progress has been made towards a global climate agreement to implement the emissions reductions required to reach this target. We use an integrated energy–economy–climate modeling system to examine how a further delay of cooperative action and technology availability affect climate mitigation challenges. With comprehensive emissions reductions starting after 2015 and full technology availability we estimate that maximum 21st century warming may still be limited below 2 ° C with a likely probability and at moderate economic impacts. Achievable temperature targets rise by up to ~0.4 ° C if the implementation of comprehensive climate policies is delayed by another 15 years, chiefly because of transitional economic impacts. If carbon capture and storage (CCS) is unavailable, the lower limit of achievable targets rises by up to ~0.3 ° C. Our results show that progress in international climate negotiations within this decade is imperative to keep the 2 ° C target within reach.</p>