Major Impacts of Climate Change on the Earth System

Table 3 Major Impacts of Climate Change on the Earth System

Temp-	[CO2]	Year in Impacts to the earth system		Region	Source
erature	ppm	which		affected
rise		impact
above		occurs
prein-
dustrial
			OBSERVED CHANGE
0.6	378	2004	Annual average temperature	Globe	IPCC TAR
			has risen by 0.6C
0.6		2004	Temperature has risen by	Arctic	ACIA 2004
			1.8C; could rise by 10C by
			2100
0.6		2004	Sea surface temperature	Globe e.g. N	IPCC 2001;
			increased by 0.6C +/-0.1C	Sea where	EEA 2004
				0.5C rise in
				15 years
0.6		2004	90% globe’s glaciers	Globe e.g.	EEA 2004,
			retreating since 1850 (not	Alps where	Street &
			attributed)	70-90% mass	Melnikov
				loss (30-40%	1990
				since 1980)
0.6		2004	Increased freshwater flux	Northern and	ECF 2004
			from Arctic rivers appears to	Western
			be already 20% of what	Europe
			would cause shutdown of
			THC
0.6		2004	Arctic sea ice extent	Arctic	Cavalieri et
			decreased by 0.30 +/- 0.03 x		al 2003
			10 6 km(2)/10 yr from 1972
			through 2002, but by 0.36 +/-
			0.05 x 10(6) km(2)/10yr from
			1979 through 2002, indicating
			an acceleration of 20% in the
			rate of decrease.
0.6		2004	3.7+/- 1.6C warming/century	Antarctic	Vaughan et
			observed	Peninsula	al 2003
0.6		2004	N hemisphere snow cover	N	EEA 2004
			decreased by 10% since 1966	hemisphere
0.6		2004	Measured spring snowpack	Switzerland	Scherer et al
			decreased in Alps		2004
0.6		2004	Measured spring snowpack	Cascades &	Mote 2005
			declined, (not attributed)	N California,
			correlated with rising	USA
			temperature/declined
			precipitation
0.6		2004	Arctic sea ice reduced by 15 -	Arctic	ACIA 2004
			20%

0.6	2004	Bottom melt rates of	Antarctic	Rignot &
		Antarctic glaciers increase by		Jacobs 2002
		1m/year for each 0.1C rise in
		ocean temperature
0.6	2004	Some evidence that	Amazon	ECF 2004
		savannaisation of parts of
		Amazon triggered by land use
		change interacting with
		warming
0.6	2004	Greenland ice sheet losing	Greenland	Rignot &
		mass (not attributed)		Jacobs 2002
0.6	2004	West Antarctic Ice Sheet	Antarctic	Rignot &
		losing mass overall;		Jacobs 2002
0.6	2004	Larsen B ice shelf collapse;	Antarctic	Rignot et al
		subsequent ice discharge from		2004
		land (not attributed)
0.6	2004	Increase in global sea level	Globe	Thomas et al
		of 1.8 mm/year : about 50%		2004
		of this caused by melting of
		terrestrial ice (remainder
		from thermal expansion of
		water), of which 0.4 mm/yr
		from non-polar glaciers, 0.4
		mm/yr from Greenland,
		estimated 0.2 mm/yr from
		West Antarctic Ice Sheet

0.6	2004	Green biomass increased by	Europe	EEA 2004
		12% (not attributed)
		PREDICTED CHANGE
1.5	7m sea	Onset of complete melting of	All coastal	Gregory
	level	Greenland ice: when	regions;	2004
	rise	complete 7 m of additional	many world
	over	sea level rise	cities
	betwee		inundated
	n x and
	y years
2 – 3??	CO	Collapse of Amazon	S America,	Cox et al
	2doubli	rainforest replacing forest by	also globe	2004, Betts
	ng +/-	savannah: enormous		2005
	?q	consequences for biodiversity
		and human livelihoods
2 to 3?	550 +/-	Conversion of terrestrial	Global	Cox et al
	?? but	carbon sink to carbon source,		2000, Cox
	inevita	due to temperature-enhanced		2005, ECF
	ble at	soil and plant respiration		2004
	some	overcoming CO2-enhanced
	point	photosynthesis. Resulting in
		desertification of many world

Regions as there is widespread loss of forests and grasslands, and accelerating warming through a feedback effect

Any			Release of C to atmosphere	Global	Neilsen 1993
			due to deterioration of
			ecosystems at rapid rates of
			temperature change
	Double		Net primary production	Globe	Betts 2005
			increases by 10%
	Double		Runoff increases by 12%	Globe	Betts 2005
2.3	2100		Collapse of thermohaline	Globe;	Schlesinger
			circulation: Maximum	cooling NW	2005
			likelihood of shutdown of 4 in	Europe,
			10 for climate sensitivity of	warming
			3C (and climate sensitivity	Alaska and
			could lie between 1.5 and	Antarctic,
			11C)	decreasing
				rainfall in S
				America
1.5			Probability of collapse		Yohe,
			exceeds 50%		Schlesinger
					and
					Andronova
					in press.
1 – 3			Collapse of thermohaline	Northern and	Rahmsdorf
			circulation affecting fisheries,	Western	in ECF 2004
			ecosystems, agriculture:	Europe
			expert opinion probabililty “a
			few percent”
3	2100	700	THC collapse		O’Neill &
					Oppenheime
					r 2002;
					Keller et al
					2004
2 – 4.5			Potential to trigger melting of	Globe	ECF 2004
			the West Antarctic Ice Sheet
			raising sea levels by a further
			5 to 6 m ie 60 to 120
			cm/century
4 – 5			Expert opinion: probability of	Northern and	Rahmsdorf
			thermohaline shutdown up to	Western	in ECF 2004
			or above 50%	Europe
Comme			THC collapse, Greenland Ice		Discussed at
nt:			Sheet melt and West		conference
			Antarctic Ice Sheets may
			interact in ways that we have
			not begun to understand
			Potential release of methane	Globe:	IPCC 2001

	from melting tundra and	feedback
	clathrates from shallow seas;	accelerating
	add recent publication	warming
	mentioned at conference that
	we may be nearing this point
2100	Acidification of the oceans	World	IPCC 2001;
	falls by 0.4: may disrupt	oceans	Blackford
	marine ecosystem		2005; Archer
	functioning, in turn reducing		1995
	buffering capacity of oceans
	(positive feedback)
2250	Acidification falls by 0.77	World	IPCC 2001;
		oceans	Blackford
			2005
	Increased variability in	Asia,	IPCC 2001,
	summer monsoons	Australia	Steffen 2005,
	exacerbating flood/drought		Lal 2003
	damage
16	Permanent El Nino	Globe	Navarra
xCO2			2005

*Note: at 0.6C some observed changes are marked as “not attributed”. In these cases calculations of the cause of these changes has not yet been made. They are listed because they are changes which are consistent with the patterns of change predicted to result from anthropogenic climate change.

Earth system

Table 3 Major Impacts of Climate Change on the Earth System