* Aims to halve Scope 3 emissions by 2050
* To merge upstream and downstream businesses (Adds details)
LONDON, Feb 12 (Reuters) - BP pledged to sharply reduce its carbon emissions by 2050 as part of a reinvention of the 111-year old company by newly-appointed chief executive Bernard Looney.
BP on Wednesday set more ambitious targets than rivals such as Royal Dutch Shell and Total but fell short of commitments made by smaller Spanish peer Repsol.
We need to reinvent BP," Looney said in a statement.
The worlds top oil and gas companies have come under heavy pressure from investors and climate activists to fall in line with the 2015 Paris climate accord which aims to limit global warming to below 2 degrees Celsius from pre-industrial levels.
"The worlds carbon budget is finite and running out fast; we need a rapid transition to net zero. We all want energy that is reliable and affordable, but that is no longer enough. It must also be cleaner," he added.
U.S. groups such as Exxon, Chevron and ConocoPhillips are far less ambitious with their greenhouse gas related targets than their European rivals.
BP said it plans to halve the intensity of the carbon emissions of the oil and gas products it sells, known as Scope 3 emissions, by 2050.
A pioneering "Beyond Petroleum" plan in the early 2000s to build a large renewables business ended with huge losses.
Over the past two years, Europes top oil and gas companies have ceded some ground to growing investor pressure to tackle climate change by reducing carbon emissions.
Intensity-based targets measure the amount of greenhouse gas (GHG) emissions per unit of energy or barrel of oil and gas produced. That means that absolute emissions can rise with growing production, even if the headline intensity metric falls.
Scope 3 emissions vastly exceed greenhouse gases caused by the production of crude oil, natural gas and refined products, including electricity generation, typically by a factor of about six among oil majors, according to Reuters calculations.
In one of its biggest changes, BP will dismantle the traditional model of an oil and gas production, or upstream, unit and a refining, trading and marketing, or downstream, unit.
Its new organisation includes four units: Production and Operations; Customers and Products; Gas and Low Carbon Energy; and Innovation & Engineering. (Reporting by Shadia Nasralla, editing by Louise Heavens and Alexander Smith)