If it is assumed that the future will resemble the recent past – very unlikely – then there is little to be concerned about. A rate of warming of 0.07oC/decade implying moderate climate sensitivity to carbon dioxide and centuries – in a worst case scenario – to reach an impossibly misguided target of 2OC. Climate shifts abruptly and unpredictably – driven by internal variability – every 20 to 30 years. The shifting climatic regimes are evident in climate records – the most significant for atmospheric temperature are discussed below. Anastasios Tsonis and colleagues used a network math approach to demonstrate for the first time in 2007 that climate shifts are consistent with the theory of synchronous chaos – showing in a quantitative way that climate is a coupled nonlinear system. It is more evidence in a growing body of work showing that a fundamental rethink of climate mechanisms is overdue. The practical policy implication is that the atmosphere may not warm for another decade or two – and that cooling after that is possible. Why wait? Assume for a moment – if you can – that this is possible.
Source: Swanson and Tsonis 2009
Ocean and atmospheric indices – in this case the El Niño Southern Oscillation, the Pacific Decadal Oscillation, the North Atlantic Oscillation and the North Pacific Oscillation – can be thought of as chaotic oscillators that capture the major modes of climate variability. Tsonis and colleagues calculated the ‘distance’ between the indices. It was found that the climate system ‘synchronize’ at certain times and then shifts into a new state. The shifts are marked by an increased synchronisation followed with an increase in coupling. Climate shifts are marked by changes in the state of the Pacific Ocean and in the trajectory of atmospheric temperature.
Understanding synchronised chaos is essential to understanding the nature of internal variability in a complex and dynamic climate system. More or less significant climate shifts occur every 20 to 30 years.
Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. For example, roughly half the north Atlantic warming since the last ice age was achieved in only a decade, and it was accompanied by significant climatic changes across most of the globe. Similar events, including local warmings as large as 16°C, occurred repeatedly during the slide into and climb out of the last ice age. Human civilizations arose after those extreme, global ice-age climate jumps. Severe droughts and other regional climate events during the current warm period have shown similar tendencies of abrupt onset and great persistence, often with adverse effects on societies. (NAS, 2002)
Climate is chaotic at all scales. It is a very powerful mechanisms for climate changes in wind, cloud, ice, dust, hydrology, vegetation, etc. Some of these changes are significant for decadal variability of surface temperature.
A cool PDO and a La Niña are the result of cold and carbon dioxide and nutrient rich water from the oceanic abyss upwelling on the eastern Pacific margin. The upwelling sets up feedbacks in winds and currents that create the characteristic cold ‘V’ of the cool Pacific mode. Rainfall increases in Australia, Indonesia, China, Africa and the Middle East – the atmosphere cools.
Source: NASA 2008
The PDO is predominantly cooler or warmer for periods of 20 to 30 years. It was in a warm mode – warming the planet – from 1977 to 1998.
ENSO shows the same periodicity in the frequency and intensity of La Niña and El Niño. La Niña dominant to 1976 and El Niño dominant to 1998 – with mixed signals since.
This study uses proxy climate records derived from paleoclimate data to investigate the long-term behaviour of the Pacific Decadal Oscillation (PDO) and the El Niño Southern Oscillation (ENSO). During the past 400 years, climate shifts associated with changes in the PDO are shown to have occurred with a similar frequency to those documented in the 20th Century. Importantly, phase changes in the PDO have a propensity to coincide with changes in the relative frequency of ENSO events, where the positive phase of the PDO is associated with an enhanced frequency of El Niño events, while the negative phase is shown to be more favourable for the development of La Niña events. (Verdon and Franks, 2006)
We may assume that the 1946 to 1976 cool period – cool PDO and dominant La Niña – and the 1977 to 1998 warm period – warm PDO and El Niño dominant – cancelled out and that the net increase over the period was the anthropogenic warming component. The residual is about 0.4 degrees C – or 0.07 degrees C/decade. Although it seems likely that some of the net late 20th century warming was the result of solar and ENSO variability over much longer periods. And also that the future of climate is quite unpredictable.
Responding to unpredictability and risk requires building resilience in both natural systems and human communities. Much of the 180 billion tons of carbon lost from vegetation and soils can be sequestered. A significant proportion of the 345 billion of tons of carbon emitted from other sources since 1950. Carbon sequestration in soils has major benefits in addition to offsetting anthropogenic emissions from fossil fuel combustion, land use conversion, soil cultivation, continuous grazing and cement manufacturing. Restoring soil carbon stores increases agronomic productivity and enhances global food security. Increasing the soil organic content enhances water holding capacity and creates a more drought tolerant agriculture – with less downstream flooding. There is a critical level of soil carbon that is essential to maximising the effectiveness of water and nutrient inputs. Global food security, especially for countries with fragile soils and harsh climate such as in sub-Saharan Africa and South Asia, cannot be achieved without improving soil quality through an increase in soil organic content. Wildlife flourishes on restored grazing land helping to halt biodiversity loss.
Increased agricultural productivity, increased downstream processing and access to markets build local economies and global wealth. Economic growth provides resources for solving problems – conserving and restoring ecosystems, better sanitation and safer water, better health and education, updating the diesel fleet and other productive assets to emit less black carbon, developing better and cheaper ways of producing electricity, replacing cooking with wood and dung with better ways of preparing food thus avoiding respiratory disease and again reducing black carbon emissions. The warming potential of black carbon is equal to that of carbon dioxide emission from electricity production – but is given little attention in the public sphere. A global program of agricultural soils restoration is the foundation for balancing the human ecology. In this international year of soils – Some 100 nations have so far committed to increasing soil carbon by 0.4% per year. As a global objective and given the highest priority it is a solution to critical problems of biodiversity loss, development, food security and resilience to drought and flood.