The following is an open letter from Edward Mazria, FAIA, CEO of Architecture 2030 to United Nations Framework Convention on Climate Change Secretariat Executive Secretary Patricia Espinosa, urging the UNFCCC to regularly revise carbon emissions reduction targets to meet an overall reduction of 65% by 2030.

Dear Ms. Espinosa,

I am writing to urge the UNFCCC to take immediate action and publicly post and widely disseminate the 67% probability 1.5˚C carbon budget, and to regularly revise the emissions reduction targets and dates as necessary to meet that budget.

By way of background, after decades of discussion and negotiations, 195 countries signed the Paris Climate Agreement in 2015 to stabilize greenhouse gas concentrations “at a level that would prevent dangerous anthropogenic interference with the climate system”, and to limit the global temperature increase to “well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius”.

As a follow up to the Paris Agreement, the 2018 IPCC Special Report: Global Warming of 1.5˚C (IPCC SR15) modeled the difference in environmental impacts of a 1.5˚C temperature limit and a 2˚C limit. According to the report, just a half a degree of warming difference can avoid many of the devastating and intensifying impacts of climate change.

Within the 2018 Special Report is the global carbon budget for a 67% probability of limiting global warming to 1.5˚C – 420 GtCO2 beginning January 1, 2018. As of the beginning of 2020, the CO2 emission budget remaining is 340 GtCO2; approximately 40 GtCO2 are emitted annually and we have already used up 80 GtCO2. The remaining carbon budget of 340 GtCO2 equates to CO2 emissions reductions of 65% by 2030, and zero emissions by 2040, as illustrated in the following graphic:

Courtesy Architecture 2030

As can be seen, immediate actions are critical to accomplish the 65% emissions reduction target by 2030. If we act quickly and responsibly, we have an excellent chance of staying within the 1.5˚C budget. We have all the tools, policies, strategies, products, and affordable renewable energy needed to do so, as outlined in the International Energy Agency’s “World Energy Outlook 2020”.

Currently, many governments, industries, businesses, NGOs, organizations, and UN affiliates are using outdated targets and timelines, or targets that make us unlikely (less than a 50% probability) to meet the remaining budget and the 1.5˚C warming limit. For example, they have been setting targets like “net-zero emissions by 2050” because it is easier to put off reductions into the distant future where it will fall to others to act. Erroneous claims of currently meeting the 1.5˚C budget only ensures that the world will fail to avert the worst effects of climate change.

As the leader of the international entity tasked with supporting the global response to the threat of climate change, it is incumbent upon the UNFCCC Secretariat to provide updated accurate targets on its websites and in its communications of the emissions reductions and timelines necessary to achieve the 1.5˚C global warming threshold.


Edward Mazria FAIA, FRAIC

CEO and Founder

Architecture 2030