Page 216 - Materials Chemistry, Second Edition

202 R.K. Rosenbaum et al.

atmospheric thermodynamics (i.e. energy absorption via evaporation and con-
densation) and cloud formation
• Intense tropical cyclone activity increased in the North Atlantic since 1970
• Heavy precipitation and consequent flooding (North America and Europe)
• Droughts
• Wildfires
• Heat waves (Europe, Asia and Australia)
• Alteration of hydrological systems affecting quantity and quality of water
resources
• Negative impacts of climate change on agricultural crop yields more common
than positive impacts
• Shifting of geographic ranges, seasonal activities, migration patterns, abun-
dances and species interactions (including in biodiversity) by many terrestrial,
freshwater and marine species
• Changes in infectious disease vectors

The continuation and intensification of already observed effects as well as those
not yet observed (but predicted by models as potential consequences offurther global
warming) depend on the future increase in surface temperature which is predicted
using atmospheric climate models and a variety of forecasted emission scenarios
ranging from conservative to optimistic. Given the inertia of atmospheric and
oceanic processes and the global climate, it is expected that global warming will
continue over the next century. Even if emissions of GHGs would stop immediately,
global warming would continue and only slow down over many decades. The fol-
lowing effects are not yet observed and highly debated in the scientific community;
hence consensus or general agreement regarding their likelihood is not established.
Nevertheless, they are possible impacts and should be seen as part of the possible
effects of global warming, especially when considering longer time horizons.
• Slowing down of the thermohaline circulation of cold and salt water to the ocean
floor at high latitudes of the northern hemisphere (e.g. Gulf stream), among
other things responsible for global heat distribution, oceanic nutrient transport,
the renewal of deep ocean water, and the relative mildness of the European
climate. This circulation as shown in Fig. 10.6 is driven by differences in the
density of water due to varying salinity and differences in water temperature,
and might be affected by freshwater inflow from melting ice, decreasing sea
water salinity and consequently reducing its density and the density gradient
between different oceanic zones.
• Increasing frequency and intensity of “El Niño” events while decreasing that of
its counterpart “La Niña” might be possible, although it is unclear to what extent
this is influenced by global warming. One possibility is that this effect only
occurs in the initial phase of global warming, while weakening again later when
the deeper layers of the ocean get warmer as well. Dramatic changes cannot be
fully excluded based on current evidence; therefore, this effect is considered a
potential tipping element in our climate.