Another climate report is out – what’s new? Many of the previous reports have presented updated status on the climate and familiar topics such as temperature, precipitation, ice, snow, wind, and storm activities.

The latest report Climate change, impacts and vulnerability in Europe 2016 from the European Environment Agency (EEA) also includes an assessment of hail, a weather phenomenon that is often associated with lightening (a previous report from EASAC from 2013 also covers hail).

Usually, there has not been a lot of information about hail, but that is improving. Still, the jury is still out when it comes to hail and climate change:

Despite improvements in data availability, trends and projections of hail events are still uncertain.

More importantly, the report contains important update on the state of the usual weather elements in Europe. I will not give a lengthy account of the scope of the report due to its wide range of topics, but rather give a brief list of some quotes to show some of the strongest conclusions:

“European land temperatures in the decade 2006–2015 were around 1.5 °C warmer than the pre‐industrial level, and they are projected to continue increasing by more than the global average temperature increase.”

“Heavy precipitation events have increased in several regions in Europe over recent decades, in particular in northern and north‐eastern Europe.”

“the probability of occurrence of various recent heat waves and other damaging extreme weather and climate events in Europe has substantially increased as a consequence of anthropogenic climate change”

“The vast majority of glaciers in the European glacial regions are in retreat.”

“Snow cover extent in the northern hemisphere has declined significantly since the 1920s, with most of the reductions occurring since 1980.”

“The severity and frequency of droughts appear to have increased in parts of Europe, in particular in southern Europe and south‐eastern Europe.”

“Earlier spring advancement is observed in many plant species, and the pollen season starts earlier and is longer.”

“Many species have changed their distribution range, generally northwards and uphill, and these trends are projected to continue.”

Some results, however, were more ambiguous such as long-term trends in wind speeds and storm statistics:

Observations of wind storm location, frequency and intensity show considerable variability.

The report also has a strong emphasis on hydrology, for which the status also is less clear-cut than the results for temperature and precipitation.

River flows have generally increased in winter and decreased in summer, but with substantial regional and seasonal variation.

Many rivers are regulated and it is therefore difficult to compare old records before such interventions with the modern situation. Other consequences and impacts of climate change beside hydrology include ecosystems, e.g.

Changes in temperature cause significant shifts in the distribution of marine species towards the poles, but also in depth distribution.

The report also discusses the effects climate change has on society such as health issues, agriculture, transport, energy, tourism, and the economy. It is meant to assist science-based decision-making, and there is a growing recognition of the costs connected to climate change:

Climate‐related extreme events accounted for almost EUR 400 billion of economic losses in the EEA member countries over the period 1980−2013.

‘Climate change, impacts and vulnerability in Europe 2016’ presents a number of important climate indicators, and I think it’s good that the report discloses that the data also is accessible from the European portal CLIMATE-ADAPT. However, you will need to search for a little while within the portal before you can get a copy of the data. At least for some types of data, you would get to the (external) source after a few clicks (I didn’t check them all).

The report provides a useful overview (Table 1.7) of the data availability for all the climate indicators discussed therein, and places them in the context with emissions scenarios and climate simulations on which the future projections are based. The overview suggests that the assessments rely on variable amounts of data and model simulations, and in most cases fairly small ensembles.

The global climate models (GCMs) are for all intents and purposes able to simulate observed natural variations such as the North Atlantic Oscillation (NAO) and Atlantic Meridional Overturning Circulation (AMOC). Both the NAO and the AMOC have a dominant influence on regional variations over Europe on time scales of a decade [1]. These fluctuations are ‘non-deterministic’ which means that we cannot give an accurate forecast of their exact future state.

The statistical properties of these phenomena, however, are more readily predictable. We need sufficiently large samples to estimate the parameters which determine their statistical behavior. The objective is quantify the range of possible outcomes (and likelihoods) of such variations which come on top of the long-term changes caused by greenhouse gas forcings.

A tricky question is whether the individual GCM simulation can be considered as an independent sample or whether there is a need to include many different types of models made up of different model components [2].

The GCM results then need to be downscaled to provide more reliable details about the local climate. In some cases, the future projections for the local effects rely on several regional climate models (RCMs) but only a few GCMs (e.g. the projections for river flow involves 4 GCMs and 7 RCMs). The downscaling of these results are strictly not independent if they are based on the same GCM simulation because one GCM run provides the same description of the regional (“large-scale”) conditions.

In other words, the results presented in ‘Climate change, impacts and vulnerability in Europe 2016’ represent uncertain estimates due to the reliance on a limited set of data. They give an indication of the direction of how things change, but are still not sufficient for providing a full account of the range of potential future outcomes.

‘Climate change, impacts and vulnerability in Europe 2016’ may be relevant to other continents than Europe, even if it has a regional focus. Many of the issues and weather phenomena are similar across the world, and Europe has one of the most comprehensive meteorological and hydrological observational networks in the world.

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