An Overview of Paleo-Climate Evidence in Egypt
25
3 Causes of and Consequences of Global
Paleoenvironmental and Climatic Changes
A vast number of studies have emphasized the initial causes of the climatic and
palaeoenvironmental changes that took places during the Earth’s history. The proposed scenarios depend on multidisciplinary studies includes paleontological, sedimentary, volcanic, asteroid impact, and paleo-CO 2 and paleo-temperature trends.
The causes of climatic and palaeoenvironmental changes can be summarized as one
or even more of the following:
Extraterrestrial impacts (Fig. 3) that led to a sequence of processes includes
explosion, fragmentation, cratering, melting and vaporization of the immediately
surrounding rocks [15–17].
(a) The results of any asteroid impact depend mainly on the crater size and includes
earthquakes, tsunami waves, high level of aerosols input into the atmosphere
such as sulfur and carbon dioxides, mercury, dust. The consequences of the
impact are increasing the acid rain due to the high greenhouse gases level in
the atmosphere changing the climate to hot humid climate, increase in ocean
acidity [18]. The long-lasting of the greenhouse gases in the atmosphere leads
to prolongation of the period of high global temperature that affect on both
biosphere and hydrosphere [19].
(b) The large volcanic eruptions, The Large Igneous Provinces (LIPs) thought to
play a significant role in global climatic changes that can be observed in Paleorecords [20]. Several efforts were made to link the main mass extinctions and
oceanic anoxia events resulted from climatic and paleoenvironmental changes
to the major volcanic eruptions even (Fig. 3), though it’s still in debate [21, 22,
23, 24, 9, 25, 20, 26].
(c) Several Maas extinctions and hyperthermal events show a good correlation
with the LPIs occurred during their time and their relation is well established
such as Late Ordovician mass extinction [27] Middle Permian and the PermoTriassic mass extinction event [21, 28, 29, 30], end-Pliensbachian extinction
and Toarcian [31, 32] end-Triassic mass extinction [33], early Cretaceous [34];
Cretaceous-Tertiary Mass Extinction events [21, 35, 36, 9, 37, 38, 39] end of
Cretaceous [37] and recently PETM [40, 41]. The large volcanic eruption has
the same effect as the extraterrestrial impacts.
(d) Huge CO 2 release, several sources of the CO 2 were proposed explaining several
climatic changes in the Earth’s history. Wildfires, extensive burning of peat and
coal deposits linked with the arid period [42]; (2) thermogenic methane linked
to hydrothermal injection in organic-rich sediments [43–45]. (3) the drying of
isolated epicontinental seas which led to rapid oxidation of organic matter [46],
(4) melting of the methane-rich permafrost [47] and (5) Catastrophic methane
release from the continental sheilf [48, 49]. All these sources can be led to
increasing the greenhouse conditions and forces the climatic changes.
25
3 Causes of and Consequences of Global
Paleoenvironmental and Climatic Changes
A vast number of studies have emphasized the initial causes of the climatic and
palaeoenvironmental changes that took places during the Earth’s history. The proposed scenarios depend on multidisciplinary studies includes paleontological, sedimentary, volcanic, asteroid impact, and paleo-CO 2 and paleo-temperature trends.
The causes of climatic and palaeoenvironmental changes can be summarized as one
or even more of the following:
Extraterrestrial impacts (Fig. 3) that led to a sequence of processes includes
explosion, fragmentation, cratering, melting and vaporization of the immediately
surrounding rocks [15–17].
(a) The results of any asteroid impact depend mainly on the crater size and includes
earthquakes, tsunami waves, high level of aerosols input into the atmosphere
such as sulfur and carbon dioxides, mercury, dust. The consequences of the
impact are increasing the acid rain due to the high greenhouse gases level in
the atmosphere changing the climate to hot humid climate, increase in ocean
acidity [18]. The long-lasting of the greenhouse gases in the atmosphere leads
to prolongation of the period of high global temperature that affect on both
biosphere and hydrosphere [19].
(b) The large volcanic eruptions, The Large Igneous Provinces (LIPs) thought to
play a significant role in global climatic changes that can be observed in Paleorecords [20]. Several efforts were made to link the main mass extinctions and
oceanic anoxia events resulted from climatic and paleoenvironmental changes
to the major volcanic eruptions even (Fig. 3), though it’s still in debate [21, 22,
23, 24, 9, 25, 20, 26].
(c) Several Maas extinctions and hyperthermal events show a good correlation
with the LPIs occurred during their time and their relation is well established
such as Late Ordovician mass extinction [27] Middle Permian and the PermoTriassic mass extinction event [21, 28, 29, 30], end-Pliensbachian extinction
and Toarcian [31, 32] end-Triassic mass extinction [33], early Cretaceous [34];
Cretaceous-Tertiary Mass Extinction events [21, 35, 36, 9, 37, 38, 39] end of
Cretaceous [37] and recently PETM [40, 41]. The large volcanic eruption has
the same effect as the extraterrestrial impacts.
(d) Huge CO 2 release, several sources of the CO 2 were proposed explaining several
climatic changes in the Earth’s history. Wildfires, extensive burning of peat and
coal deposits linked with the arid period [42]; (2) thermogenic methane linked
to hydrothermal injection in organic-rich sediments [43–45]. (3) the drying of
isolated epicontinental seas which led to rapid oxidation of organic matter [46],
(4) melting of the methane-rich permafrost [47] and (5) Catastrophic methane
release from the continental sheilf [48, 49]. All these sources can be led to
increasing the greenhouse conditions and forces the climatic changes.