OBR warns UK public debt could triple by 2070s
Ageing, climate change, geopolitics boost spending
Tighter policy or faster growth needed to stop debt rise
Labour government blames Conservatives for fiscal woes
Demographic challenges faced by most Western countries

LONDON, Sept 12 Reuters British public debt is likely to soar to triple its current level over the next 50 years if future governments do not take action, due to pressures from an ageing population, climate change and geopolitical risks, a watchdog said on Thursday.

The Office for Budget Responsibility OBR said debt was on course to rise from nearly 100 of annual gross domestic product now to 274 of GDP by the mid 2070s, and could top 300 of GDP due to other risks similar to the forecast it gave last year.

OBR board member David Miles, a former Bank of England policymaker, said this scale of debt increase would not be sustainable.

With unchanged policies and with growth mediocretopoor as it has been over the last couple of decades, something39;s got to give, he told a news conference.

Under the OBR projections, which are based on recent demographic trends and policy as it stood shortly before a national election in July, public spending would rise to more than 60 of GDP over the next 50 years. Spending is about 45 of GDP now, its highest sustained level since the 1970s.

Public spending needs would be reduced if there was global action to limit climate change which might trim debt levels by 10…