President Obama in the State of the Union
Address, Jan 2015.
Photo Credit: National Memo. |
“No challenge poses a greater threat to
future generations than climate change,” argued Barack Obama in January 2015.
This recognition of climate change by the world’s second largest polluter , a nation who previously remained firmly outside the Kyoto Protocol and scuppered the UN’s Copenhagen climate-change conference in 2009 should give a slight glimmer of hope for the upcoming COP21. But why is climate change such a great challenge? What are the facts behind it? Does it really merit a new international agreement on climate in Paris?
This recognition of climate change by the world’s second largest polluter , a nation who previously remained firmly outside the Kyoto Protocol and scuppered the UN’s Copenhagen climate-change conference in 2009 should give a slight glimmer of hope for the upcoming COP21. But why is climate change such a great challenge? What are the facts behind it? Does it really merit a new international agreement on climate in Paris?
The global concentration of carbon dioxide in the atmosphere, measured in parts per million (ppm), is the primary indicator of recent climate change. The highly cited Hansen et al. (2008) paper investigated the target level of atmospheric CO2 that humanity should aim for in order to preserve a planet similar to that on which life and civilization have developed and adapted. When the paper was written, these 'safe levels' required CO2 to be reduced from 385ppm (parts per million) to at most 350ppm. However, the latest observations of atmospheric CO2 for September 2015 show these levels to have risen to 396.86 (fig. 1). Even more alarmingly atmospheric CO2 levels broke the 400ppm milestone in March this year sending a stark warning before COP21.
Figure 1: Monthly mean atmospheric carbon dioxide at Mauna Loa Observatory, Hawaii. |
The IPCC, the leading international body for the assessment of climate change reported in its Fifth Assessment (2013) that the Warming of the climate system is 'unequivocal', with many of the observed changes since the 1950's being unprecedented over decades to millennia highlighting how human influence on the climate system is clear. The full report is 1535 pages long and so some of the key findings from the summary are presented below.
- Anthropogenic greenhouse gas (GHG) emissions since the pre-industrial era have driven large increases in the atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) (fig. 2).
Figure 2: Credit: IPCC (2014). |
- About half of anthropogenic CO2 emissions between 1750 and 2011 have occurred in the last 40 years (fig. 3)
Figure 3: Credit: IPCC (2014). - Globally averaged combined land and ocean surface temperature data show a warming of 0.85°C over the period 1880 to 2012 (fig. 4)
Figure 4: Credit: IPCC (2014). |
- Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010. The upper 75m warmed by 0.11°C per decade between 1971-2010
- The ocean has absorbed about 30% of the emitted anthropogenic CO2, causing ocean acidification; the pH of ocean surface water has decreased by 0.1, corresponding to a 26% increase in acidity.
- The average rate of ice loss from glaciers around the world, excluding glaciers on the periphery of the ice sheets, was very likely 226 [91 to 361] Gt yr−1 (gigatonnes) over the period 1971 to 2009, and very likely 275 [140 to 410] Gt yr−1 over the period 1993 to 2009.
- Over the period 1901 to 2010, global mean sea level rose by 0.19m [0.17 to 0.21] (fig. 5). The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.
Figure 4: Credit: IPCC (2014).
In
addition a highly topical piece of research was published this year on
the Planetary
Boundaries Framework. Although arguably subjective and somewhat
controversial the paper provides a useful framework for assessing and defining
a safe operating space for humanity based on the biophysical processes that
regulate the Earth system. The research suggests that four of the ES
processes/features (climate change, bio-sphere integrity, biogeochemical flows,
and land-system change) exceed the proposed planetary boundaries.
The planetary boundaries framework Steffan et al. (2015) |
The recognition that human activities have had
major environmental impacts on the climate system has led to considerable
debate within the scientific community with a push for the Anthropocene (the
period of time when humans have had major, global impacts on the earths
systems) to be designated as a formal geological epoch, leaving the era of the
Holocene (Mackay, 2015). Much of the debate surrounds
the Anthropocene's start date. Crutzen and Stoermer (2000) who originally
proposed the epoch suggest its beginning at 1850 in line with the start of the
industrial revolution. More recently Steffan et al. (2015) propose the beginning
of the great acceleration (post 1950) as a start date arguing that only after
this point is there is 'clear evidence for fundamental shifts in the state and
functioning of the Earth System that are beyond the range of variability of the
Holocene and driven by human activities', based upon socio-economic and earth
system trends. However, Ruddiman (2013) suggests that pre-industrial
temperature changes caused by humans could be more than double the
anthropogenic warming caused by the industrial era, more than doubling the
cumulative effects of humans on global temperature to date.
It has been widely reported that that a 'hiatus'
in the upward trend of global surface temperatures occurred between 1998 and
2012. However, a recent paper in Science suggests that this hiatus never
occurred. Global trends are higher than those reported by the IPCC, especially
in recent decades, and that the central estimate for the rate of warming during
the first 15 years of the 21st century is at least as great as the last half of
the 20th century. It should come as no surprise then that 2014 was the hottest year on record with Noaa
reporting that global average temperatures over land and sea surface for
the year were 0.69°C above the 20th-century average. Again, July 2015 was the hottest month on the
earth since records began.
So what do these changes mean for the global
economy? A new study published in Nature argues that we have dramatically
underestimated the damage that anthropogenic climate change will do the global
economy. The paper investigated data from 160 countries between 1960-2010 and
found that productivity peaks at an average local temperature of 13°C. If
regional temperatures are cooler, then warming benefits the local economy, but
past that peak temperature, warming reduces economic productivity. There was
only weak evidence that global warming would not impact economic growth in
wealthy countries, even though it has previously been assumed wealthier countries would have
the resources to adapt to a changing climate. If future adaptation follows
previous progress, unmitigated warming is expected to reshape the global
economy by reducing average global incomes roughly 23% by 2100. Moreover poor
counties will be preferentially harder hit reinforcing the reality that poorer
countries which arguably contribute least to the problem are the most
vulnerable to the consequences.
Another somewhat alarming discovery published in Nature climate change estimates the economic
impact of carbon dioxide and methane being released from permafrost as it thaws
resulting from rapid arctic warming. It found that by 2200, when these
emissions are expected to peak, the costs could be 0.7% of global GDP. These
findings are echoed by Mark Carney, the governor of the bank of England who
last month warned that measures to avoid catastrophic
climate change are essential to avoid financial crisis and falling living
standards calling climate change the 'tragedy of the horizon' - imposing a
cost on future generations that the current generation has no direct incentive
to fix.
This blog has only begun to scratch the surface
into the very real, alarming and critical threat of anthropogenic climate
change that faces humanity. I believe the evidence is too great for international
inaction to continue. I have broadly outlined the extent and scope of
the problem and why the Paris talks in December really are Crunch time for a
new legally binding agreement that will enable us to combat climate change
effectively and boost the transition towards resilient, low-carbon societies
and economies. Next time I will discuss what climate changes are projected for the future. A particular focus will be on the 2°C target and why it has been set as the goal for global climate policy (and the
aim for COP21) following the Copenhagen talks in 2009.
Very well written and well argued! I do agree with you on the fact that a new legally binding agreement is necessary to tackle climate change issues. However, seeing the failure to establish a binding agreement and instead settling on the 'Copenhagen Accord' in 2009, do you really think the outcome of Paris 2015 will be a binding agreement with a top-down approach (similar to Kyoto)?
ReplyDeleteHi!
DeleteFantastic question. Sorry it has taken me so long to respond but following all the research I have done for my blogs In the lead up to COP21 I now think I can give you a good answer.
I am very hopeful that a new top down legally binding agreement can be reached. As I concluded in my blog on bottom up versus top down approaches, to me, it seems illogical to completely abandon a top down system that as been at the forefront of negotiations for a new system that is unproven and no more guaranteed to ensure success. Furthermore the addition of the INDCs at COP21 not only signifies the modification of climate governance to include bottom up approaches but also construct a path of ever-increasing emission reductions asking countries what they are willing and able to do.
I am very hopeful that the INDCs will, as the UNFCCC claim that the INDCs will act as the foundations for a broader new climate agreement that will support sustainable actions nationally and globally
Although may positives can be taken from the speeches delivered by leaders on day one of the conference there are mountains to climb over cuts, long term goals, finance, equity, and the principle that the rich countries should act first and dig deeper because they are responsible for the historical emissions.
Although a legally binding agreement still remains the mantra of COP21 I don't think anyone knows what the outcome is going to really be.
I really like your summaries of the IPCC's findings and the relation to the issues at hand! But do I agree with the comment above (by Unknown). Do you feel that legal international agreements which are top down are the most effective? Or is there another solution that is more effective?
ReplyDeleteHi Louis,
DeleteGreat question! Please find my response on the link below.
http://paris-crunchtime.blogspot.co.uk/2015/11/top-down-or-bottom-up-different.html