No doubt sea levels are rising – the only question is how much it’ll change our world

JUNE 16, 1904, was a sunny day in Dublin, if its depiction in Ulysses is to be believed. Sunlight is everywhere as the novel opens, with Stephen Dedalus demurring from joining the ablutions in the 40 Foot, noting instead that all Ireland is washed by the Gulf Stream before walking into literary history across Sandymount Strand.

The actual weather records for June 16, 1904, can be found in our national archive which dates back to the 1800s. This is a powerful and important national and international record. It can tell us much about the stability and variability of our weather and climate.

Ireland experiences very active weather. Changes can be rapid and difficult to plan for, but our extensive records allow us to work out the averages and the ranges that are the annual, seasonal and monthly norms.

Standard climate data are based on analysis of 30 years of weather data, and there have always been extremes which emerge naturally from the complex and dynamic systems which give us our weather.

Thirty years was considered long enough to capture weather extremes, as well as normal conditions. It is these extremes that cause us most problems.

We have used this historical analysis of weather data and linked analysis of floods and droughts to inform the design and construction of key infrastructure.

In fact, all our systems and behaviours have, in one way or another, developed to thrive in the weather norms and to cope with the standard extremes.

But that sense of security about what we can expect is changing. We now understand that our historical records are not going to be a good predictor of the future.

This should be included in strategic plans and designs for future infrastructure, and investments.

Also, we have to assess how existing systems and structures will deal with future weather and climate.

So how do we do this?

The National Adaptation Framework published last year is a good start. It provides a key piece of the jigsaw in developing national resilience to the adverse impacts of climate change. The sectoral and local plans to be published next year are further steps.

However, key uncertainties remain, including about the rate and extent of climate change.

The 2015 Paris Agreement sets global limits and targets for actions to address the causes of climate change, but we already know that we are collectively not on target to meet its goals, well ahead of the first global stock-take due in 2023 that will assess progress under the agreement.

How, then, to plan and invest is a key question. It will require innovative approaches to taking account of the uncertainties and associated risks.

Flood defences are a clear example, but this is also the case for other infrastructure and investments. These should include consideration of climate scenarios that exceed the Paris Agreement temperature goals.

This is also where science comes in. Later this year, the Intergovernmental Panel on Climate Change, the IPCC, will publish a report on global warming of 1.5C.

It will tell us more about the expected impacts at that level of warming, which may be reached by the middle of this century.

However, there are key gaps in, and limits to, our scientific understanding.

One of these is just across our western horizon.

Below Greenland, a striking anomaly in the global temperature record exists. It is an area of cooling, a “blue blob” in the otherwise red globe of higher temperatures.

A recent study published in the journal ‘Nature’ suggests that this blob is due to a weakening of the major ocean cycle that gives us the Gulf Stream. There are indications that, as global temperature increases, this feature will also increase.

The North Atlantic Ocean and the Gulf Stream dominates our weather and climate. Changes to these can significantly shift our weather systems and climate, with impacts extending across northern Europe.

Current climate models suggest that in a warmer world we may get more stable conditions, such as those we are currently experiencing, but when storms come they will be more intense and damaging.

These model projections are not forecasts. More work is needed to understand what is happening in the north Atlantic region.

IT is in Ireland’s strategic interest to ensure that such scientific gaps are addressed and that uncertainties are reduced through investment in integrated research and observations systems. This will assist in planning for the impacts of climate change and reducing associated risks, making these more cost effective.

However, what all models show is that sea-level rise will continue, at least until the end of this century even after the global temperature has stabilised.

It is only the rate and extent of sea-level rise that remains to be better determined.

‘Ulysses’ is widely regarded as one of the great novels of the 20th century. Its author is said to have claimed that Dublin could be rebuilt based on it.

The Dublin of Bloomsday, June 16, 2104, may be very different to that of 1904, and crossing Sandymount Strand a very different experience.

The greatest story of the 21st century is likely to be about how the world we have known throughout human history has been changed. Changed utterly.

Climate models suggest that in a warmer world we may get more stable conditions, but when storms come they will be more damaging