From the UNFCCC:

Fact sheet: The need for strong global action on climate change

Climate change is one of the most fundamental challenges ever to confront humanity. Its impacts are already showing and will intensify over time if left unchecked.

The overall ambition to reduce greenhouse gasses remains inadequate. If all current pledges and plans to cut or limit emissions were delivered completely and on time, global emissions would still keep growing in the next 10 years, under present trends. More stringent actions to reduce greenhouse gas emissions, in particular by industrialised nations, cannot be postponed much longer. Otherwise, the window of opportunity to keep the average global temperature rise below 2 degrees C is in danger of closing, and the door to a 1.5 degrees world will slam shut.

Serious impacts are associated with this scenario, including sea-level rise, shifts in growing seasons, and an increasing frequency and intensity of extreme weather events such as storms, floods and droughts.

The United Nations climate change negotiations offer a historical opportunity to step up international action on climate change. Strong action is essential to the global transition into green economic growth, and, most urgently, to help the world, especially the most vulnerable, adapt to impacts that are now inevitable.
Why must the world act as one?

Dealing decisively with climate change is key to ensuring sustainable development, poverty eradication and for safeguarding economic growth. Science indicates that inaction will be more costly than acting now. Economic development needs to be moved onto a low-emissions and climate-resilient path.

Stringent emission reductions are required to keep global temperature increases and corresponding climate change impacts as low as possible. A move towards a low-emissions society clearly requires a reorientation of global economic growth patterns. This necessitates innovative changes in the short and medium-term in technology in all sectors of the economy.

According to the International Energy Agency, global energy demand will grow 55% by 2030. In the period up to 2030, the energy supply infrastructure worldwide will require a total investment of USD 26 trillion, with about half of that in developing countries. If the world does not manage to green these investments by directing them into climate-friendly technologies, emissions will go up by 50% by 2050, instead of down by 50%, as science requires.

How can a global deal unleash protection for those who will suffer most from the adverse impacts of climate change?

Climate change is becoming a major threat to efforts to promote sustainable economic and social development and to reduce poverty. Impacts are already showing and are very likely to increase as climate change takes hold. Consequently, it is absolutely essential that adaptation be accorded the same level of priority and support as mitigation. Adaptation thus needs to be one of the cornerstones of strengthened global cooperation on climate change. Impacts fall disproportionately on the poor, those who do not have the means to deal with them.

Impacts highlighted by the IPCC include:

• Widespread melting of glaciers and snow cover will reduce melt water from major mountain ranges (e.g. Hindu Kush, Himalaya, Andes), where more than one billion people currently live;

• Approximately 20-30% of plant and animal species are likely to be at increased risk of extinction if increases in global average temperature exceed 1.5-2.5°C;

Countries recognize that strong action on adaptation is required, which addresses the needs of developing countries for scaled up financial support, technology and capacity-building. Increased investment in adaptive capacity, such as strengthening the ability of countries to reduce disaster risk, will safeguard economic progress already made, on the way to achieving overall development goals.