Citing “clear and growing” human influence on the climate system, a United Nations report issued has warned that if left unchecked, climate change will increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.

Echoing that dire warning, UN Secretary-General Ban Ki-moon said that if the world maintains its “business as usual” attitude about climate change, the opportunity to keep temperature rise below the internationally agreed target of 2 degrees Celsius, “will slip away within the next decade.” 

“With this latest report, science has spoken yet again and with much more clarity. Time is not on our side…leaders must act,” declared the UN chief, in Copenhagen, Denmark on an official visit that included a press conference to launch the final installment of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC).

According to a press release from the panel, the so-called “Synthesis Report” confirms that climate change is being registered around the world and warming of the climate system is unequivocal. Since the 1950s many of the observed changes are unprecedented over decades to millennia. 

“Our assessment finds that the atmosphere and oceans have warmed, the amount of snow and ice has diminished, sea level has risen and the concentration of carbon dioxide has increased to a level unprecedented in at least the last 800,000 years,” said Thomas Stocker, Co-Chair of IPCC Working Group I, which participated in the compilation of the final report along with two other expert working groups. 

Calling the report the “most comprehensive assessment of climate change” ever carried out, the Secretary-General urged worldwide action in light of its stark findings, saying that “even if emissions stopped tomorrow, we will be living with climate change for some time to come.” 

Yet, the “good news is that if we act now, we have the means to build a more sustainable world,” he said, explaining that quick and decisive action that draws on many readily available tools and technologies can put the world on the right track. It was a myth that climate action would be costly, he said, stressing that in fact, inaction “will cost much, much more.”

R. K. Pachauri, Chair of the IPCC, underscored that the means to limit climate change are at had. “The solutions are many and allow for continued economic and human development. All we need is the will to change, which we trust will be motivated by knowledge and an understanding of the science of climate change.”