The first installment of the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), published today, adds new evidence to the reality of climate change and the responsibility of human activity as the cause of serious alterations to the climate system and ultimately responsible for global warming.
The first installment of the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), published today, adds new evidence to the reality of climate change and the responsibility of human activity as the cause of serious alterations to the climate system and ultimately responsible for global warming. The study, dedicated to the physical basis of climate science, confirms that the scale of global climate disruptions is unprecedented in centuries or even millennia, and projects temperature rises of more than 1.5ºC – or even 2ºC – unless the international community achieves drastic reductions in greenhouse gas emissions.
“It is time to act and to do it now,” said the Minister for Ecological Transition and the Demographic Challenge, Teresa Ribera. The new contributions of the first installment of the Sixth Evaluation Report “leave no room for doubt, nor can there be palliatives. Climate changes are happening at an increasingly accelerated pace and scientific evidence pushes governments and global society as a whole to accelerate the pace of transformation of our development model and our economic system to face the great threat posed by climate change,” added the Third Vice-President of the Government. This transformation cannot be postponed “and we cannot postpone the adoption of corrective measures not with the horizon of 2050, but not even that of 2030”, he stressed.
A MORE UP-TO-DATE AND ACCURATE VIEW
The IPCC assessment reports are the best reference on the state of scientific knowledge on climate change. These reports are prepared thanks to the collaborative and selfless work of thousands of leading scientists from the different fields of knowledge. And they are also the main scientific reference in the process of international consultation on climate change that is being developed around the United Nations Framework Convention on Climate Change and the Paris Agreement.
The Report of Working Group I of the IPCC’s Sixth Assessment Report (AR6) takes advantage of a series of scientific advances that have occurred since the previous report (2014) saw the light of day: the improvement of observed data series and paleoclimatic data, new climate simulations (based on climate models), new analyses and methods that allow multiple lines of work to be combined. For the first time in an IPCC report, future changes in global temperature, ocean warming, and sea level are calculated through the combined use of projections, observed data, and updated assessments of climate sensitivity. The result is a better understanding of human influence on an expanded set of variables.
INTERACTIVE ATLAS WITH SPANISH WEIGHT
One of the main novelties of this Group I issue is its Interactive Atlas, an online tool that will allow some of the results of the report to be explored on a regional scale, in particular global projections of climate change under different scenarios and for different levels of warming. Until now, IPCC products were static documents (printed or electronic). On this occasion, and for the first time, the report is associated with an interactive product whose development has incorporated improvements previously applied to the Spanish viewer of climate change scenarios. The Spanish scientist José Manuel Gutiérrez, from the Institute of Physics of Cantabria, and the Spanish National Research Council (CSIC) have played a leading role in the development of this instrument.
Along with Gutiérrez, three other Spanish researchers have participated as main authors: Francisco Doblas Reyes (Barcelona Supercomputing Centre), Sergio Faria (Basque Climate Change Centre) and Sergio Vicente-Serrano (Pyrenean Institute of Ecology). Gutiérrez and Doblas-Reyes have acted as coordinating authors.
In addition, a dozen more researchers nominated by Spain have participated in the two remaining working groups of the Sixth Evaluation Report, whose deliveries are scheduled for the first quarter of 2022, with the percentage of scientists in the three working groups as a whole being 43%.
LAND AND MARINE WARMING
Among other data updated by the report released today by the IPCC, it stands out that in the period 2011-2020 the average temperature on the surface has been 1.09ºC higher than that of the period 1850-1900, an increase that has been greater in terrestrial areas (+1.59ºC) than in marine areas (+0.88ºC).
In addition, the upper layer of the ocean (between 0 and 700 meters deep) has been warming since the 70s of the last century, and it is extremely likely that the main causative factor is human influence. CO2 emissions are also the main cause of global ocean acidification. Global mean sea level has risen by about 20 cm between 1901 and 2018. Between 1901 and 1971 the sea level rose at an average of 1.3 mm/year. It went to 1.9 mm/year between 1971 and 2006 and rose to 3.7 mm/year in the period 2006-2018.
UNPRECEDENTED DISRUPTIONS
The report of the panel of experts published today shows the magnitude of a long list of serious climate alterations of unprecedented intensity. Among other considerations, the scientists note that the current concentrations of CO2 in the Earth’s atmosphere are unprecedented at least in the last 2 million years. Meanwhile, the concentrations of methane (CH4) and nitrogen oxide (N2O) are higher than those recorded in the last 800,000 years.
Likewise, the rise in mean sea level observed since 1900 has been faster than that recorded in any previous century, at least in the last 3,000 years. Climate change caused by human activity is behind the observed increases in climate extremes.
There is almost total certainty that warm extremes (including heat waves) have become more frequent and intense in most of the areas that emerged since the 1950s, while cold extremes (including cold waves) have become less frequent and severe. Some recently observed warm extremes would have been extremely unlikely in the absence of human influence.
An increase, frequency and intensity of episodes of very heavy rainfall has been detected since the 1950s in those areas where sufficient data are available. In the specific case of the Mediterranean region, the report attributes the observed increase in extreme high temperature records and agricultural and ecological droughts to human activity.
PROJECTIONS INTO THE FUTURE
The global surface temperature will continue to increase at least until the middle of this century in all the emission scenarios analyzed. Unless strong reductions in greenhouse gas emissions are achieved in the coming decades, both global increases of 1.5ºC and 2ºC will be exceeded over the course of this century.
According to projections, greater global warming will intensify the global water cycle, increasing its variability. A warmer climate will intensify very dry and very wet weather events, increasing the frequency and intensity of droughts and floods. Many of the changes caused by past greenhouse gas emissions will be irreversible on timescales from centuries to millennia, most notably changes affecting the oceans, polar ice caps, and sea level.
Understanding climate responses and the range of potential consequences, including those that result in low-probability but high-severity impacts, is essential for climate services, climate risk assessment and climate change adaptation planning.
