Angela Merkel has conceded Germany’s record on reducing carbon emissions was “not sufficient” to meet the global warming targets of the Paris climate agreement, as the chancellor reflected on the achievements and missed opportunities of her 16-year leadership.

Speaking at the last of her annual summer press conferences on Thursday before stepping down as leader of Europe’s largest economy after federal elections on 26 September, Merkel said Germany “has done a lot” to recalibrate its economy in the face of the climate crisis, increasing the share of renewables in its energy mix from 10% to 40%, and lowering carbon emission by 20% in the period from 1990 to 2010, and by another 20% in the 10 years since.

The 67-year-old nonetheless conceded that “what has been achieved is not sufficient” when measured against the Paris agreement’s target to limit global warming to well below 2C, preferably to 1.5C, compared with pre-industrial levels. Not just Germany, but the whole world had failed to meet its targets, she said.

“I am equipped with sufficient sense for science to see that objective circumstances demand that we can’t continue at the current pace but have to up the tempo,” Merkel said.

While Germany alone could not change the world climate, she argued, “the manner in which we do it can set an example that others follow”.

Merkel, who was environment minister under Chancellor Helmut Kohl from 1994 to 1998, said the fight for joint global steps towards more efficient climate protection had “shaped my entire political work”.

She defended her government’s 2011 decision to phase out nuclear power by 2022, which critics say has made the country more reliant on coal power. “For Germany, the die has been cast,” she said. “I don’t see a government of the future changing anything in that respect.”

The issue of the climate emergency has returned to the top of the political agenda after record rainfall and flash floods last week devastated large parts of western Germany, killing at least 179 people and leaving transport and energy infrastructure in parts of Rhineland-Palatinate and North-Rhine Westphalia in disarray.

Germany’s national weather service said on Thursday that regions hit by the floods last week could receive more heavy rain at the weekend.

Merkel said the effort to rebuild houses, railways and energy lines in the flooded region would be a monumental undertaking that would require her efforts “until the last day” of her chancellorship.

On Wednesday her cabinet approved emergency financial aid worth EUR200m (GBP170m) for people affected by flooding, with state governments expected to match the federal aid programme.

More than 4,500 civil defence workers, firefighters and soldiers have been deployed to help with cleanup efforts in the badly affected Ahr valley region of Rhineland-Palatinate.

Merkel said the extent of the damage had yet to be determined “but it is immense”.

At the start of the wide-ranging one-and-a-half hour press conference, Merkel also expressed her concern about the “worrying dynamic” of the Covid-19 pandemic in Germany, saying the Delta variant was driving another wave of “exponential growth” despite 60% of the German population having received at least one shot of vaccine.

Germany’s disease control agency, the Robert Koch Institute, on Thursday registered 1,890 new infections over the past 24 hours and an incidence rate of 12.2 new cases per 100,000 people over the last week, up from a low of 4.9 in early July.