Great Stories

Climate varies over different time scales, from years to hundreds of millions of years, and each periodicity is a manifestation of separate forcing mechanisms (section 2.4). In addition, different components of the climate system change and respond to forcing factors at different rates; in order to understand the role such […]

The causes of centennial to millennial scale climate fluctuations are not well understood. Three forcing mechanisms have been considered: volcanism (section 2.6.3), solar variability (section 2.5.3) and internal ocean circulation dynamics (section 2.6.4). Detailed studies of volcanic events of the last 100 years indicate that significant hemispheric and global cooling […]

Ozone (O3) in the stratosphere filters out harmful ultra-violet radiation from the Sun, and so protects life on Earth. Recently, there have been fears about the destruction of the ozone layer, principally over the Antarctic (Farman et al., 1985; Hofmann et al., 1992), but increasingly now over the Arctic regions […]

Although GCMs provide the most detailed simulations of future climate change, computational constraints preclude their use in sensitivity studies that allow one to investigate the potential effects of real-world future greenhouse gas emissions. By using simpler climate models, it is possible to estimate future changes in the global-mean surface air […]

Global climate change results from a combination of periodic external and internal forcing mechanisms, and a complex series of interactive feedbacks within the climate system itself. These climate changes occur over a whole range of time scales from a few years to hundreds of millions of years. The traditional view […]

Historical records have been used to reconstruct climates dating back several thousand years (i.e. for most of the Holocene). Historical proxy data can be grouped into three major categories (see Table 3.1). First, there are observations of weather phenomena per se, for example the frequency and timing of frosts or […]

GCMs have estimated the CO2 doubling temperature change in the absence of feedback processes to be approximately 1.2C. The existence of feedback loops within the climate system results in a climate sensitivity of 1.5C to 4.5C, and makes an otherwise linear association between radiative forcing and global temperature distinctly non-linear. […]

The first UK national strategy, in response to the Framework Convention, aimed to stabilise CO2 emissions at 1990 levels by 2000. As a consequence of the Kyoto Protocol, the UK is now committed to a 12% reduction in greenhouse gas emissions by 2008 to 2012 (as part of a Europe-wide […]

In addition to these gases, water vapour (H2O) is a vital atmospheric constituent, averaging about 1% by volume, with significant variations across spatial and temporal scales. Its presence in the atmosphere forms part of the global hydrological cycle. Water vapour, being the most important natural greenhouse gas on account of […]

Aerosol particles in the 0.1 to 1.0m diameter range have the highest efficiency per unit mass for optical interactions with incoming solar radiation due to the similarity of particle size and radiation wavelength. Sulphate aerosols and organic matter (Table 6.6) are therefore most effective at scattering and absorbing the short-wave […]