The Minister for Ecological Transition and the Demographic Challenge, Teresa Ribera, stressed the urgency of acting to tackle climate change.

The Intergovernmental Panel on Climate Change (IPCC) has published the first installment of the Sixth Assessment Report with the contribution of Working Group I, which deals with the physical scientific basis of climate change, adding new evidence to the reality of climate change and the responsibility of human activity as a cause of serious alterations to the climate system and ultimately responsible for global warming.

Faced with this scenario, the Minister for the Ecological Transition and the Demographic Challenge, Teresa Ribera, has stated that “it is time to act and to do it now”, adding that the new contributions of the first installment of the Sixth Evaluation Report “leave no room for doubt, nor can there be palliatives”. He also stressed that “climate alterations 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”. The third vice-president of the Government also stressed that 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”.

The study, developed around the United Nations Framework Convention on Climate Change and the Paris Agreement, has consulted more than 14,000 articles and references published so far and has had the participation of more than 230 experts from 66 countries. It highlights that the scale of global climate disruptions is unprecedented in centuries or even millennia. In addition, it projects temperature rises of more than 1.5 ºC – or even 2 ºC – unless the international community achieves drastic reductions in greenhouse gas emissions.

Some of the data provided by the IPCC report highlight that in the period 2011-2020 the average surface temperature has been 1.09 ºC higher than that existing in the period 1850-1900, an increase that has been greater in terrestrial areas (+1.59 ºC) than in marine areas (+0.88 ºC).

Regarding warming in marine areas, the study states that the upper layer of the ocean (between 0 and 700 meters deep) has been warming since the 70s of the last century, highlighting human influence as a more than likely causative factor.

Similarly, the study also includes carbon dioxide emissions as the main cause of global ocean acidification. Global mean sea level has risen by about 20 centimeters between 1901 and 2018. Between 1901 and 1971 the sea level rose at an average of 1.3 millimeters per year. Going from 1.9 millimetres per year between 1971 and 2006 to 3.7 millimetres per year in the period 2006-2018.

Unprecedented changes

The report of the panel of experts also highlights the magnitude of a long list of serious climate alterations of unprecedented intensity. Some of those considerations have to do with current concentrations of carbon dioxide in Earth’s atmosphere that scientists have not seen in at least the last 2 million years. Likewise, the concentrations of methane (CH4) and nitrogen oxide (N2O) are higher than those recorded in the last 800,000 years.

Meanwhile, the average sea level observed since 1900 has risen faster than that recorded in any previous century, at least in the last 3,000 years.

The document assures that human activity would be behind the alterations observed in climate extremes and that they would have been extremely unlikely in the absence of this influence. That is why there is practically 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.

As for rainfall episodes, an increase in the frequency and intensity of rainfall has been detected very strongly 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.

According to the projections, the document states that the global surface temperature could increase at least until the middle of this century in all the emissions scenarios analyzed. Unless strong reductions in greenhouse gas emissions are achieved in the coming decades, they would exceed both global increases of 1.5 ºC and those of 2 ºC.

It also refers to the fact that 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. The study highlights that many of the changes caused by greenhouse gas emissions in the past will be irreversible on timescales from centuries to millennia, most notably changes affecting the oceans, polar ice caps and sea level.

For all of the above, the work suggests that knowing the responses of the climate and the range of possible consequences, including those that translate into impacts of low probability, but high severity, is essential for climate services, climate risk assessment and planning for adaptation to climate change.

Interactive Atlas and the presence of Spanish researchers

Until now, IPCC products were static documents (printed or electronic), but this time an Interactive Atlas is included for the first time, 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. In the development of this viewer, improvements have been incorporated previously applied to the Spanish viewer of climate change scenarios. Spanish researchers have participated in this instrument.

The next installments of the report, scheduled for the first quarter of 2022, will have the contribution of two remaining working groups with more than a dozen researchers nominated by Spain, constituting 43% of the presence of female scientists in the three working groups as a whole.