Past Earth Network

Forecasts of climate rely on model projections, but derivation of
sophisticated climate models from first principles is not currently
feasible. Therefore, evaluating climate models with observations is
essential. The development and improvement of global climate models
is currently only based on comparison with and tuning to historical
observations of climate (the instrumental record). Model simulations
of the present climate are well-tuned and are in general agreement
with each other. However, there is no clear relationship between
model performance for present day and model behaviour for projections.
Models show a range of sensitivities when predicting the future
climate response to the emission of greenhouse gases. This indicates
that the evaluation of models using observations of historical climate
is insufficient. It is very difficult to reduce uncertainties on
projections based on the instrumental period only and the use data
from earlier periods is critical.

A wide variety of different climate states are recorded in the
geological record (spanning greenhouse to icehouse scenarios). The
modelling of past climates, in combination with data from the
geological record, provides a unique laboratory to evaluate the
ability of models to forecast global change. While data is available
from numerous intervals in Earth
history, analysis is often constrained by the availability of material
of the correct age and data collection is often very time consuming
and expensive (e.g. for marine sediment cores). For this reasons, it
is important that data on past climate and environments is utilised
optimally and that challenges resulting from sparsity of the data as
well as from temporal and spatial uncertainties are addressed in the
best way possible.

The earth system modelling and proxy reconstruction communities often
have little contact with professional statisticians. Even in
publications, ad-hoc methods are used instead of established
statistical "best practice". If inappropriate statistical methods
are used, inference about models and the earth system will be weakly
supportable or plainly wrong. To avoid these problems and to realise
the opportunity of improved earth system forecasting, sound
statistical methods as advised by statisticians must be used. On the
other hand, use of appropriate statistical methodology is often made
difficult due to sparsity of data or lack of resources, and
statisticians are not always aware of the resulting restrictions on
the applicability of methods. Statisticians need to develop awareness
of the restrictions and requirements caused by the sparsity of
palaeoclimate data and the high complexity or climate models.

The Past Earth Network will develop a shared, multi-disciplinary
vision for addressing the challenges encompassed by the following four
network themes. (1) Quantification of error and uncertainty of data:
The uncertainties inherent in different forms of climate data must be
well-understood. This is particularly challenging for palaeoclimate
data, since uncertainties are often large and varied. (2)
Quantification of uncertainty in complex models: The uncertainties in
the output of the (complex and high-dimensional) models in use must be
well-understood. (3) Methodologies which enable robust model-data
comparison: Appropriate methods for model-data comparison must be
used, taking into account the nature and sparsity of data. (4)
Forecasting and future climate projections: This theme synthesizes the
results from the first three themes in order to assess and ultimately
improve the ability of climate models to forecast climate change.

By addressing these four challenges, results produced by the Past
Earth Network will help to better understand and reduce the
uncertainties in climate forecasts and ultimately will contribute to
the development of better climate forecasts.

The Past Earth Network strives to obtain a better understanding and a
quantification or reduction of uncertainties, both in Earth system
models and in environmental forecasts. Such efforts will have a broad
impact on society and policy.

Policy makers are required to meet legally binding climate targets.
For example, the Climate Change Act 2008 requires the UK to reduce
green house gas emissions to 80% of the 1990 levels by 2050. The
responsibility of implementing this policy lies with the Department of
Energy & Climate Change (DECC), the Committee on Climate Change
(CCC), the Department for Environment, Food & Rural Affairs (DEFRA),
the Department for Transport, and the Environment Agency (EA) and the
UK research funding councils. Reductions of the uncertainties in
earth system forecasts, achieved from the results of theme~4 in the
Past Earth Network, will allow for better management of risk for
policy makers, thus assisting in the planning and implementation of
required changes. Ultimately, the Past Earth Network aspires to
reduce the forecasting error in climate projections, allowing for more
accurate planning and resource allocation.

National policy decisions are informed by scientific activities like
the Intergovernmental Panel on Climate Change (IPCC). We have
discussed our network proposal with project partner Valerie
Masson-Delmotte (Coordinating Lead Author of Chapter 5 of Working
Group 1 of the IPCC 5th Assessment Report), and Valerie was very
positive about our proposal. While the corresponding section of the
IPCC has now concluded, future IPCC-type activities will benefit from
the results of the network.

One of the main aims of the network is identification of the main
challenges which must be overcome to obtain better climate forecasts.
Knowledge about these challenges will allow the UK research councils
to make better decisions about where to focus future research funding
in this area.

Economic impact of the network will come from the ability of
geosciences-based industries to build on better knowledge of
uncertainties related to the earth system, thus reducing economic
risk. For example, in the petroleum and mineral exploration
industries, results of climate model experiments can help to reduce
risk by helping to better predict pertinent aspects of the petroleum
system. Andrew Davies (Head of Innovation at Neftex Petroleum
Consultants Ltd.) is a member of our steering committee and has helped
to shape the network to achieve maximal impact of the network to
related industries.

Institutions like the British Geological Survey address climate change
issues through a variety of channels, with the aims of observing past
and present climate, understanding those observations, and ultimately
forecasting future climates and the environmental responses to those
climates. Michael Ellis (Head of Climate Change Science at the BGS)
is a member of our steering committee and has helped to shape the
network to fully realise impacts from network activities for the BGS.

Finally, the network will inform public discussion with the help of
outreach activities. The public will benefit from better awareness of
the challenges faced and results achieved by the Past Earth Network,
by being able to make better choices about their own life styles and
about what the UK should do to achieve its climate targets.